SpaceX delivered the US, French and Russian astronauts a day after launching them from Cape Canaveral.
Last month's medical evacuation was NASA's first in 65 years of human spaceflight.
One-of-four astronauts launched by SpaceX last northern summer suffered what officials described as a serious health issue, prompting their hasty return.
That left only three crew members to keep the place running - one American and two Russians - prompting NASA to pause spacewalks and trim research.
Moving in for eight-to-nine months are NASA's Jessica Meir and Jack Hathaway, France's Sophie Adenot and Russia's Andrei Fedyaev.
Meir, a marine biologist, and Fedyaev, a former military pilot, have lived up there before. During her first station visit in 2019, Meir took part in the first all-female spacewalk.
Adenot, a military helicopter pilot, is only the second French woman to fly in space. Hathaway is a captain in the US Navy.
NASA has refused to divulge the identity of the astronaut who fell ill in orbit on January 7 or explain what happened, citing medical privacy.
The ailing astronaut and three others returned to earth more than a month sooner than planned.
They spent their first night back on earth at the hospital before returning to Houston.
23°C