The combined enrollment at OSU's Stillwater and Tulsa campuses stood at 23,044 on Monday — a 4.8 percent increase over the spring 2012 semester.
OSU generally calculates the combined enrollment at the two campuses, because many students enroll in courses at both campuses during the same semester.
That increase comes a semester after OSU welcomed the largest incoming freshman class of any public university in state history.
The 2012 freshman class numbered 4,306, which topped the previous record of 4,053.
That record was set at the University of Oklahoma in 2011.
Many of the state's other colleges, including OU and the University of Central Oklahoma, start classes next Monday.