Although anemia is a frequently observed complication of phlebotomies for laboratory tests in neonates, this problem has received little attention in adult populations. We analyzed the phlebotomy records of 100 hospitalized patients and found that 50 patients who spent all of their hospitalization in general wards had blood samples drawn an average of 1.1 times a day. A mean volume of 12.4 ml a day was drawn, and the total volume drawn during their entire hospitalization was 175.0 ml. In contrast, 50 patients who spent part or all of their hospitalization in an intensive care unit were phlebotomized a mean of 3.4 times a day, for a mean volume of 41.5 ml of blood drawn a day and a total volume of 762.2 ml. Patients in the intensive care unit who had arterial lines had more blood drawn (944.0 ml), more often (4.0 times a day), than patients in the intensive care unit who did not have such lines (300.9 ml; 1.9 times a day). Of 36 patients who received transfusions, 17 (47 percent) had large losses from phlebotomy (greater than 180 ml of red cells) that contributed to their transfusion requirements. We propose the use of sample tubes of the size used in pediatrics, batching of requests for laboratory tests, and review of the cumulative volume of blood removed from individual patients as approaches to reducing blood loss from phlebotomy.