For each patient, laboratories usually collect more blood than is needed for specific determinations. We reviewed the amount of blood collected for laboratory measurements for an entire hospital stay of 113 patients admitted during a 1-week period to a medical ward or to a medical intensive-care unit in our tertiary-care facility. The amount of blood obtained was also compared with the minimal amount needed for analysis for 18 of the most frequently ordered laboratory tests in our facility. For routine collections, a mean of 45 times the required volume of specimen (range, 2 to 102 times) was obtained. For optimal utilization of laboratory services, both the positive and the negative consequences of testing must be thoughtfully considered. Two potential adverse effects of withdrawal of blood for laboratory determinations are iatrogenic anemia and infection. Moreover, the cost of care is increased with additional analyses. Practical strategies for decreasing the amount of blood collected include an increased awareness of ordering practices, a thorough knowledge of the volume of blood needed for each laboratory test, experienced phlebotomy personnel, storage of blood specimens for potential subsequent use, and communication of accurate minimal volumes needed for specific measurements.