To determine the effects of body conditioning score (BCS), calving difficulty (CD) and calving season (FS) on days of peak milk yield (DPM) and peak milk production (PM), the Lactation records of 160 cows in the National Animal Breeding Institute during 1993 were analyzed. Calving season was found to be a significant (p$lt;0.05) influence on peak milk production and days of peak milk yield. DPM was longest for the spring calving season (March to May), but it was shorter for the winter (December to February), summer (June to August) and fall (September to November) calving seasons (in that order). PM was highest in the winter, but showed decreasing values in the spring, summer and fall. CD did not significantly effect DPM and PM, but there was no unitorm tendency shown. BCS did not significantly effect DPM (p$lt;0.05). Cows having a body conditioning score below 3.25 had higher milk yields than those scoring over 3.25.