Knowledge of normal values of the intraocular pressure is important for diagnosing as well as for monitoring of already verified glaucoma. The purpose of this work was to determine the mean intraocular pressure in healthy sheep using rebound tonometer. For all animals included in the study, information on age, sex, and race was obtained. Twenty five healthy sheep (Ovis aries), of the same breed (Texel), males or females with three year old were enrolled in the study. Environmental temperature was approximately 30°C. All studies were approved by the institutional Animal Care and Use Committee and were in accordance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. Owners of all sheep used in the study provided their consent prior to study enrollment. All sheep included in this study received an ophthalmic examination on both eyes. For all ophthalmic testing, animals were gently physically restrained. The intraocular pressure was measured by rebound tonometry (Tonovet®, Tiolat, Helsinki, Finland). The tonometry was performed by the same examiner and measurements were taken three times for each eye and the average was recorded as the IOP of the animal. Statistical analysis was performed using paired t-test. Values of p < 0.05 were considered significant. The mean intraocular pressure in the whole group of 50 eyes was 12.8 +/2.5 mmHg. Mean (SD) IOP in the right eye was 12.9 +/1.3 mmHg. Mean (SD) IOP in the left eye was 12.7 +/1.06 mmHg. Significant differences in IOP were not found between right and left eyes. Clinically, measurement of IOP with the rebound tonometer in sheep without anesthetic was a rapid and well tolerated procedure. Rebound tonometry could be an appropriate tonometry method for routine clinical use in sheep. Reference data will assist in diagnostic testing for ophthalmic disease in sheep.