Oklahoma State suffered a three-game series sweep at the hands of Cal Poly as the Cowboys fell to the Mustangs, 6-0, in Sunday's series finale at Baggett Stadium.
Junior starter Randy McCurry suffered the loss on the mound, allowing five runs, four of them earned, on six hits in 5.2 innings of work.
Offensively, the Cowboys collected seven hits but stranded 11 runners on the basepaths. Robbie Rea led OSU with two hits.
After 4 ½ scoreless innings, Cal Poly got on the scoreboard in the fifth, scoring four runs before the Cowboys recorded an out in the inning.
Cal Poly, who had never beaten OSU in four previous tries entering the weekend's series, tallied its final run in the seventh inning.
The Cowboys return to action with their 2012 home opener at Allie P. Reynolds Stadium when OSU takes on Dallas Baptist at 4 p.m. on Tuesday.