Objective-To measure intraocular pressure (IOP) and progesterone concentrations in cats and to examine their reproductive organs to determine whether reproductive status affects IOP in cats. Animals-75 sexually intact domestic shorthair cats scheduled to be neutered, including 28 males, 21 females not in estrus, 13 females in estrus, and 13 pregnant females. Procedures-Applanation tonometry was conducted to measure IOP and radioimmunoassay was used to determine progesterone concentrations. Reproductive organs were examined at time of surgery. Results-The IOP in female cats that were in estrus was significantly higher than IOP in female cats that were not in estrus. Progesterone concentrations significantly affected IOP in pregnant cats. Conclusions and Clinical Relevance-In cats, IOP is affected by changes in reproductive status. Such changes should be considered when interpreting tonometry results in this species.