The first Canadian astronaut to fly into space was Marc Garneau. He conducted a set of experiments (CANEX-1) for Canadian investigators in space science, space technology, and life sciences during Mission 41-G, October 5-13, 1984, aboard the Space Shuttle Challenger. Bob Thirsk was the alternate for the mission.

In January 1990, Roberta Bondar was designated as the prime Canadian Payload Specialist for the first International Microgravity Laboratory (IML-1) aboard Space Shuttle Discovery. During Mission STS-42, January 22-30, 1992, Bondar conducted 43 experiments on behalf of 13 countries. Ken Money was the alternate for this mission. 

In 1985, Steve MacLean was designated to fly with a set of Canadian experiments in space science, space technology, and life sciences called CANEX-2. The primary experiment was an evaluation of the National Research Council's experimental Space Vision System. The alternate Payload Specialist was Bjarni Tryggvason. CANEX-2 was scheduled for a mission in 1987 but was rescheduled following the Challenger tragedy. Steve MacLean and the CANEX-2 payload flew October 22 - November 1, 1992 during Mission STS-52, aboard Space Shuttle Columbia. 

Colonel Chris Hadfield was the first Canadian Mission Specialist and the first and only Canadian to board the Russian Space Station Mir during Mission STS-74, aboard the Space Shuttle Atlantis, November 12-20, 1995. Hadfield was also the first Canadian to operate the world-famous Canadarm when he successfully manoeuvred the arm to install docking modules.

Canadian talent and expertise figured prominently on Mission STS-77, May 19-29, 1996 when Marc Garneau celebrated his second flight into space. Canadian scientific experiments aboard Space Shuttle Endeavour included the Commercial Float Zone Furnace (CFZF), the Aquatic Research Facility (ARF), the Nanocrystal Get Away Special (NANO-GAS) and the Atlantic Canada Thin Organic Semiconductors (ACTORS).

Space Shuttle Columbia lifted off on June 20, 1996 on Mission STS-78, a 17-day Life and Microgravity Science (LMS) mission with Bob Thirsk aboard. Thirsk actively participated in the diverse slate of life and microgravity experiments, conducted aboard LMS, the reusable laboratory designed to allow scientists to perform experiments in microgravity conditions.

Bjarni Tryggvason, Payload Specialist for Mission STS-85 launched on August 7, 1997. His principle role on this flight was to conduct further tests of the Microgravity Vibration Isolation Mount (MIM) and perform material science and fluid physics experiments designed to examine sensitivity to spacecraft vibrations. This work was directed at developing a better understanding of the need for systems such as the MIM on the International Space Station (ISS) and on the effect of vibrations on the many experiments to be performed on the ISS.

Dave Williams began a 17-day medical research mission in space on April 17, 1998, following the flawless launch of the Space Shuttle Columbia. Williams, an emergency medical doctor, was the seventh Canadian astronaut to fly into space aboard the shuttle. He was the first Canadian to serve as crew doctor, and the first Canadian astronaut trained to conduct a spacewalk outside the orbiter, had the need arose. During Mission STS-90, also known as Neurolab, Williams and his fellow crewmembers conducted a total of 26 life science experiments designed to study the effects of microgravity on the brain and other parts of the central nervous system. These experiments in space may someday lead to new treatments for common neurological conditions such as sleep disorders, motion sickness, balance disorders and the regulation of blood pressure. Canadians designed two of the Neurolab experiments chosen by NASA for this mission: Visuo-Motor Coordination during Space flight and the Role of Visual Cues in Spatial Orientation.

Space Shuttle Discovery, with Julie Payette aboard, lifted off May 27, 1999, for a 10-day mission. On the third day, the crew of Mission STS-96 performed a rendezvous with ISS for what was defined as a logistics and re-supply mission to outfit the ISS for future flights and occupants. As Mission Specialist, Payette was responsible for numerous tasks during the mission including operating the Canadarm, supervising astronaut spacewalks, deploying the STARSHINE educational satellite and changing 18 units that are part of the solar battery system of the Russian module Zarya.

Mission STS-97, also named ISS flight 4A, was launched on 30 November 2000 from the Kennedy Space Center with Marc Garneau aboard. Garneau's third mission consisted of transporting and installing solar panels to the ISS. Space Shuttle Endeavour carried the first of four sets giant solar arrays and batteries for the ISS. Endeavour's crew conducted three spacewalks to complete connections of the solar arrays. Power from this first set of arrays, set the stage for a major expansion, and the arrival of the first laboratory.

In April 2001, aboard the Space Shuttle Endeavour, Chris Hadfield made history by becoming the first Canadian astronaut to walk in space during Mission STS-100, the ISS assembly Flight 6A. The primary purpose of the flight was to deliver, install and deploy the remote robotic arm, Canadarm2, as well as, install and retrieve the Italian-made, Raffaello Multi-Purpose Logistics Module, on the ISS. Hadfield, performed two spacewalks to install the Canadarm2, which took 14 hours 50 minutes, 400 kilometres above earth. The new arm, which is 17-metres-long, is the centrepiece of Canada's contributions to the ISS.