Nicole Turner smashed her personal best to finish fifth in the final of the 50m S6 Butterfly in Rio.
Ireland's youngest Paralympic competitor touched the wall in a time of 37.31 seconds, shaving more a second from her time in her qualifying heat.
The 14-year-old from Portarlington, Co Laois, will be delighted with such a promising start to an extensive Rio programme that sees her competing in six events in the pool, with the heats of the 50 free coming tomorrow.
Turner had been the fourth-fastest qualifier for the final in a time of 38.44 seconds, behind eventual gold medallist Ellie Robinson.
The British swimmer set a Paralympic record of 35.58 to beat defending champion and world record holder Oksana Khrul of Ukraine with Australian Tiffany Kane taking bronze.
"It's amazing, to think I'm actually here after all the years of training," Turner said. "Going out there was just amazing.
"A medal would have been good but it was my first Paralympic Games."