On a total of 150 specimens of vitreous humor the post-mortem ammonia value was determined by diffusion method. The results established that there existed a regular ammonia increase after a sudden death and that deviating high or low vitreous ammonia values are strongly correlated with the cause of death and with environmental temperature. The ammonia content of the vitreous humor extracted from both eyes at the same and at different post-mortem intervals showed no differences in the concentrations between both specimens sampled at the same moment while an obvious variation in the individual rate of the vitreous ammonia increase is found, especially when hospital cases with antemortem existing disease are concerned.