The average reproductive performance in a large purebred Hereford herd for the period from 1935 through 1952 was 1.7 services per conception, 108.2 days from calving to conception, 285.7 days gestation length, 394.2 days calving interval, 75.5 days from calving to first breeding and 31.0 days from first breeding to conception. Reproduction performance was higher in summer and fall than in spring and winter. Cows (530) were taken from the herd at an average age of 7.8 years. Cows sent to market at the end of their productive life had an average age of 9.2 years. Heritability estimates of reproductive performance were near zero. Repeatability estimates varied from 0.02 to 0.15.