One hundred three patients with ischemic heart disease (IHD) were compared with 29 patients with organic heart disease and normal coronary arteries (OHD) and with a control group of 101 patients free of heart disease and matched for age and sex. Twelve patients in the control group, 4 in the OHD group, and 34 patients in the IHD group were found to have hearing loss (HL) of different degrees, cause, and duration (P = 0.0003). Of the HL-IHD group, 19 of the 34 patients had no underlying etiologic factor compared with 4 of the 12 patients in the control group (P = 0.0005); age was not an important factor. Multiple logistic regression analysis suggests that the probability of a patient with HL of unknown etiology to have IHD is eight times greater than in individuals with normal hearing. In the HL groups (12 controls and 34 with IHD), there were no significant differences in sex, hypertension, obesity, or smoking, but there was a lower incidence of diabetes and a higher incidence of family history in the HL-IHD group than in the HL-control group. Two patients in the HL-IHD group had families with many members affected by both deafness and IHD, suggesting a heredofamilial disease. HL always preceded the clinical manifestation of IHD and appears to be an important "early marker" of a vascular or generalized arteriosclerotic process.