The production of organic acids in severe diabetic acidosis was studied to determine the contribution of various acids and to reassess alkali requirements. In 11 patients the mean total concentration of determined organic acids was 16 mEq/1., while the mean estimated base deficit was 24 mEq/1. Acetoacetic and β-hydroxybutyric acids accounted for 75% of measured organic acid. In 10 patients the mean amount of sodium bicarbonate administered for correction of the acidosis was 185 mEq, while the mean requirement was 394 mEq. These findings imply that the methods commonly used to determine the base deficit and the alkali requirements in patients with diabetic acidosis may be invalid. The prompt administration of alkali should be limited, and we suggest that the blood pH should be restored only to 7*25.