Twenty-nine healthy young male volunteers were screened by history, physical examination, urinalysis, 24 different blood tests, and electrocardiography for admission to a Phase I drug study. The protocol submitted to, and approved by, the FDA listed the normal ranges for the local laboratories and stipulated that the test results for any volunteers accepted should all he within these ranges. During screening 46 abnormal values were found in the labaratory tests. Only 4 subjects had all their test data within the “normal” range, aresult that could have been anticipated simply from the number of tests performed. These jindings indicate the need for deciding on realistic protocol criteria for studies invalving healthy volunteers.