The aim of this preliminary study was to evaluate the luteolytic competence of different PGF2α (PGF, Lutalyse) doses on d5, d7 and d9 of the estrous cycle. Nonlactating Nellore cows (n = 97) were synchronized with the 7-d estradiol benzoate + CIDR program. Cows received Estrotect patches at CIDR removal to determine estrus response. Presence of ovulatory follicle and its disappearance were confirmed 48 and 72 h after CIDR removal, respectively. Cows detected in estrus within 48 h and with confirmed ovulation 72 h after CIDR removal remained in the study (n = 68). Cows were assigned to treatments according to BW (407.9 ± 5.1) and BCS (3.01 ± 0.02, scale 1 to 5). One of 4 PGF doses were administered either 5, 7 or 9 d after estrus and confirmed ovulation (a single 12.5, 25 or 50 mg dose or 2 25 mg doses 8 h apart of dinoprost trometamine), in a 3 × 4 factorial arrangement of treatments. Presence of a corpus luteum was determined by ovarian ultrasound scan and progesterone (P4) analyses (P4 ≥ 1ng/mL) on either d 5, 7, or 9 (0h) of the estrous cycle. Blood samples were collected at 0, 24, 48 and 72 h after PGF administration to assess the incidence of luteal regression (defined as concentration of P4 < 1ng/mL at 72 h after PGF). Serum P4 concentrations were quantified using a chemiluminescent immunoassay. Data were analyzed using GLIMMIX procedure of SAS. Differences in proportion of cows that experienced luteal regression were not detected for day of cycle (P = 0.19); PGF dose (P = 0.13) or their interaction (P = 0.99). The incidence of luteal regression by day of cycle was 45.0% (9/20; 5 d), 66.6% (16/24; 7 d) and 70.8% (17/24; 9 d) and for PGF dose was 42.1% (8/19; 12.5 mg), 56.2% (9/16; 25 mg) 76.4% (13/17; 50 mg) and 75.0% (12/16; 25 + 25 mg given 8 h apart). Animal numbers used in the present study limited the capacity to determine significance of numerical differences that were observed. It is interesting that luteal regression was induced in less than 50% of cows on d 5 of the estrous cycle and in cows that received 12.5 mg of PGF. Additional research is necessary to determine the optimal dose of PGF and timing during the estrous cycle to ensure luteal regression in cyclic Nellore cows.