The yield of routinely performed annual panels of laboratory tests was examined among patients in the skilled nursing facility section of a large, multilevel, long-term-care institution. Of 9270 tests done as part of 336 annual panels in 121 patients over an eight-year period, 17% of the tests yielded abnormal results, and in 36% of the tests, abnormal results were new. Among the 336 panels, 56 (16.7%) had at least one abnormality that was believed to have resulted in some benefit to 30 (24.7%) of the patients. Many of the abnormalities that led to patient benefit could have been detected by periodic monitoring of chronic conditions and their treatment as opposed to true screening tests, and all such abnormalities could have been identified by a complete blood cell count, electrolyte determinations, renal and thyroid function tests, and a urinalysis. The results suggest that a modest panel of annual laboratory tests could limit the potential costs of screening and not result in the loss of potential benefits to patients in skilled nursing facilities.