In the young child, the ocular tension cannot be taken without general anesthesia. Most of the anesthetic drugs lower the ocular tension which may give false low results in glaucoma. Ketamine is the only practical drug elevating the ocular tension. To determine the amount of the change in ocular tension under ketamine, the ocular tension was measured under I.M. ketamine 5 to 10 mg/kg in 30 children without ocular disease. The ocular tension before the anesthesia has not been measured. As soon as the child fell asleep, the ocular tension was recorded between 15 to 20 minutes. We noticed that the ocular tension remains stable in the beginning, but that it tends to rise after eight minutes of narcosis. So the ocular tension must be measured as soon as possible after induction, as soon as the child does not react to stimuli. Abnormal ocular tensions under ketamine are discussed. The ocular tensions under two different types of anesthesia (ketamine and methohexital + Thalamonal) are compared. Some examples of ocular tensions in glaucoma under ketamine are presented.