When the late Dr. John F. Fulton contracted severe pulmonary coccidioidomycosis in January, 1942, a metastatic lesion posed the threat of further progression and fatal dissemination. The possibility that an untested and generally unavailable antibiotic, penicillin, might be of value in Fulton's illness led his physician, Dr. John Bumstead, to appeal directly to Fulton to obtain this antibiotic, but ostensibly for the benefit of another patient succumbing to hemolytic streptococcal infection. While of no value for Fulton, penicillin was highly successful in the treatment of his other patient and soon of a second one with staphylococcal sepsis and pneumonia. This penicillin, administered in March, 1942, was the first clinical trial of penicillin under the control of the Office of Scientific Research and Development. The unique contribution of Dr. Fulton and of his illness to this event is described.