Peter Wells has become the first jockey in NSW to fail a breath test on race day, a result he described as bizarre after he was taken off his only ride at Randwick on Monday.

Wells was tested at 5.10pm, 27 minutes before he was due to ride Joku in the last race at the meeting.

He returned a reading in excess of .02, the legal limit for jockeys under the Australian Rules of Racing and was suspended for six weeks effective immediately.

Wells said he had attended a family christening on Sunday and had been drinking but asked stewards if he could undergo a blood test at nearby Prince Of Wales Hospital.

Stewards denied the request and Wells was breath tested twice more at 5.15pm and 6.10pm, with all readings above the limit.

"It's bizarre," Wells said.

"I was at a family christening yesterday but I can't explain it."

Wells, who won the 2008 Metropolitan on Newport, has only been back riding for six weeks after spending 11 months on the sidelines after suffering serious injuries in a fall at Kembla Grange.

Chief steward Ray Murrihy said Wells was the first jockey to return an elevated alcohol level on a raceday.

"We have had trackwork riders fail similar tests but it has never happened to a jockey on race day before," chief steward Ray Murrihy said.

Eight jockeys were tested but the other seven returned clear samples.

Joku finished second last of 13 runners.