In the vitreous humor from three hypoxemic and one control group of pigs, hypoxanthine, xanthine, and uric acid concentrations were measured. The purine concentrations were measured before the hypoxemia, at the time of death, and 24 h post-mortem. During hypoxemia with arterial O2tension between 2.1 and 3.0 kPa [fractional inspired oxygen (FiO2) = 0.08] hypoxanthine concentrations increased from a mean basal value of 11.7 ± 5.6 µmol/L to 16.3 ± 2.4 µmol//L at the time of death (NS). Xanthine concentrations changed from a basal value of 0.3 ± 0.1 µmol/L to 0.6 ± 0.2 µmol/L (p < 0.02), and uric acid changed from 3.4 ± 1.1 µmol/L to 5.0 ± 4.5 µmol/L (NS). During hypoxemia with arterial O2tension between 3.0 and 4.0 kPa (FiO2= 0.11), hypoxanthine increased in the vitreous humor from a mean basal value of 9.1 µmol/L to 20.3 µmol/L at the time of death (p < 0.02). Xanthine concentrations increased from 0.3 µmol/L to 1.3 µmol/L (p < 0.05), whereas there was no change in uric acid concentration (basal 5.0 < 0.8 µmol/L and final 4.5 ± 1.0 µmol/L). During milder hypoxemia with arterial O2tension between 4.3 and 5.6 kPa (FiO2=0.14), or in the control group (FiO2 = 0.21), neither of the metabolites changed significantly. The vitreous humor was not stable postmortem, inasmuch as the mean concentration of hypoxanthine increased from 18.2 ± 7.7 µmol/L to 121.6 ± 57.4 µmol/L 24 h post-mortem (p < 0.01). In the same period, xanthine increased from a mean 0.9 ± 0.6 µmol/L to a mean 4.9 ± 5.2 µmol/L ( p <0.01).