Measurements of 2,3-diphosphoglycerate (2,3-DPG), adenosine triphosphate (ATP), and glutamic oxaloacetic transaminase (EGOT) in erythrocytes were performed on normal and iron deficient patients. The results show a significant elevation in the level of 2,3-DPG per red blood cell (RBC) and per gram of hemoglobin and an elevation of EGOT in the iron-deficient subjects. There was no correlation between rise in the levels of 2,3-DPG and EGOT. Neither 2,3-DPG nor EGOT correlated with the level of hemoglobin or with the mean corpuscular hemoglobin concentration (MCHC). Adenosine triphosphate was not elevated in the iron-deficient patients. Thus, elevation of 2,3-DPG level in iron deficiency cannot be explained only by a decrease in hemoglobin concentration. Other factors such as cell age and intraerythrocytic pH may influence the level of 2,3-DPG in this and possibly other anemic states.