This study aimed  to evaluate the effect of lactation on first follicular wave surge of crossbred (Gir x Holstein) dairy cattle.  Nine multiparous crossbred dairy cattle were divided according to daily milk production (Group 1 = milk production higher than average, n = 5; Group 2 = milk  production  lower  than  average,  n  =  4).  From  calving  (Day  0)  until  divergence  of  first follicular wave, ovaries  was monitored daily by ultrasound exams to observed the follicular emergence,  growth  rate,  maximum  follicular  diameter,  day  of  follicular  divergence  and ovulation. The mean of milk production was 17.4 + 6.4 L/day (n= 9). Group 1 had higher daily milk production than Group 2 (21.8 + 3.8 L/day vs. 11.9 + 3.9 L/day, P< 0.001). Data of follicular emergence were similar in both groups (P >0.05). The growth  rate of first follicular surge was higher  in  Group  2  than  Group  1  (2.0  + 0.0  mm/day  vs  1.2  + 0.6  mm/day,  P<  0.05).  The maximum follicular diameter was 11.6  + 0.9 mm (Group 1) and 13.5  + 1.7 mm (Group 2); P< 0.05. The follicular divergence occurred earlier  in Group 1 than Group 2 (12.2  + 0.8 days vs 13.7 + 0.6 days; P< 0.05). One animal of Group 2 ovulated. In conclusion, data suggested that milk production had influence on ovarian follicular dynamic after calving.Keywords: Follicle, post-partum, lactation, dairy cattle