Data from 249 and 152 records of first and second lactations, respectively, were collected from the files of Dairy Herd Improvement Association and veterinary clinical records of Holstein cows from the J. C. Penny farm of the University of Missouri-Columbia from 1977 through 1987. Incidences of cystic ovaries were .345 and .421 in the first and second lactations, respectively. Heritabilities of liability to cystic ovary development based on correlation of incidences among paternal half-sib relatives were 0.15 +/- 0.44 and 0.11 +/- 0.65 for first and second lactation records, respectively. Corresponding estimates by paternal half-sib analysis of variance, using either original or angle-transformed proportions, were assumed to be zero because sire components of variance were negative. The results suggest that individual selection based on the presence or absence of cystic ovary development would be, at best, very slow in bringing about a reduction in the incidence of this disease in dairy cattle herds.