We have previously compared the electrocardiogram of 1,299 male and female students of physical education and sports with 151 age- and sex-matched sedentary controls and found that the former had lower heart rate, longer conduction times and increased voltages. The same material of 1,450 young adult subjects was split according to sex into 617 females and 833 males in order to analyze the influence of gender on the resting 12-lead electrocardiogram. We found that females had a significant higher heart rate, shortened conduction times (PQ, Q, ventricular activation time and QRS) and a prolonged repolarization time (QTc), decreased P, Q and T amplitudes as well as indices of right, septal and left hypertrophy, and ST elevation in precordial leads were lower in females than in males. These differences were highly significant with p values less than 0.0001 for almost all parameters. Sinus bradycardia was more common in men and sinus tachycardia in women. The prevalence of other rhythms and supraventricular and ventricular premature beats was low in both sexes. AV block grade I was found in 1% of females and 3% of males (p less than 0.02). Notching of R/S in V1-V2 and incomplete right bundle branch block were less common in females (p less than 0.0001). The differences in ECG parameters between the two sexes in the total material persisted also when the athletic and control groups were investigated separately. Gender seems to be highly important for most ECG parameters in the resting ECG. This points to the necessity of discussing different upper normal limits for ECG parameters according to gender.