In 1991, the College of American Pathologists' Q-Probes quality improvement program studied precision, accuracy, and program characteristics of bedside glucose monitoring (BGM) in 605 institutions. Precision measurements made in 569 institutions were based on 15 950 quality control results. Precision, expressed as a percentage coefficient of variation, was less than 10 in almost 90% of the institutions. For accuracy, 4517 BGM results from 181 institutions were compared with clinical laboratory glucose results. Approximately 58% of BGM results were within +/-10% and 75% of BGM results were within +/-15% of the corresponding clinical laboratory results. Program characteristics associated with better performance were (1) laboratorian program responsibility, laboratorian BGM test performance, and laboratorian involvement in training; (2) a policy requiring repeated scheduled operator training and/or performance review; (3) use of an internal comparison program; and (4) participation in an external proficiency testing program. We conclude that BGM frequently does not meet quality goals and provide recommendations on how BGM programs can be improved.