RIO DE JANEIRO - Singapore swimmer Theresa Goh clocked 4min 2.37sec in the women's 200m freestyle S5 heats on Thursday.
The 29-year-old was swimming in the first of the event's two heats, finishing sixth in a race won by Israel's Inbal Pezaro in 3:03.35.
Her timing at the Rio de Janeiro Games was off her best Paralympics effort of 3:14.22 clocked at Beijing 2008.
Goh was ranked last of 12 swimmers in her category, and did not qualify for the finals this morning. Only the top eight progressed.
Goh, who was born with spinal bifida, said she was glad to get her first race in Rio out of the way.
She said: "I think my strategy was different from the other swimmers. I'm just trying to prepare for my next race. I wasn't as nervous as I thought I would be. It felt pretty ok."
She is gearing up for her pet event, the 100m breastroke SB4 on Sunday.