Heath, C. W., Jr. (Leukemia Section, CDC, Atlanta, Ga. 30333), A. L. Brodsky and A. I. Potolsky. Infectious mononucleosis in a general population. Amer J Epidem 95: 46–52, 1972.—All cases of heterophile-positive infectious mononucleosis (IM) diagnosed during 1968 in the 5-county area of metropolitan Atlanta, Georgia, were ascertained through monthly reports from all clinical laboratories in the area coupled with information obtained by phone from the physician of each new patient. A total of 575 cases among residents of the area were diagnosed in the 12-month period. Overall incidence was 45.2 per 100,000 with wide fluctuations from county to county (range 16.0 to 75.5). Incidence was highest in the 15–19-year-old age group, with the peak age for females being about 2 years younger than for males. Incidence among whites was 30 times higher than among blacks. Two seasonal peaks were apparent, one in early fall and a larger one in late winter and early spring. Very few patients (6.1%) gave a history of recent contact with other known cases of IM. These various epidemiologic findings are in accord with findings recorded in other studies. Unlike most past investigations, however, the present data are based on case surveillance in a large general population.