The effects of unilateral forced nostril breathing on the intraocular pressures of right and left eyes was studied in 24 male and 26 female right-handed right and left nostrils significant adults. In men, the forced breathing through both the right significantly decreased the intraocular pressures of both right and left eyes. For women, the forced breathing through right nostril did not affect the intraocular pressures of right and left eyes, and the forced breathing through left nostril also had no effect oil the intraocular pressure of right eye, although it decreased the intraocular pressure of left eye significantly. These results show that unilateral forced nostril breathing decreases intraocular pressure especially in men, perhaps increasing sympathetic nervous system activity.