Reproduction is associated to the profitability of beef herds, which affects the level of productivity and is influenced by nutritional level. The objective of this study was to evaluate the effect of protein and energy supplementation, before and after parturition, on reproductive variables of Nellore primiparous cows extensively raised in the Brazilian tropical savannah. Eighty pregnant heifers with parturition estimated for a 45 d period during the dry season were randomly divided into four treatments: Control, received a mineral salt and urea mixture pre and postpartum; PRE, protein-energy mixture from the 210th gestational day until parturition; POS, protein-energy mixture from parturition until 90 d afterwards; PREPOS, protein/energy mixture from the 210th gestational day until the 90th day after parturition. Number of days to complete uterine involution (UI) was 37.0 (Control); 31.3 (PRE); 33.1 (POST) and 25.3 (PREPOST) with differences (P<0.05). Calving Interval (CI) was 370.4 (Control), 369.5 (PRE); 365.9 (POST) and 343.7 (PREPOST) days, with differences (P<0.05). Pregnancy rate (PR) was 64.7%; 76.5%; 65.0%; and 55.0%, respectively, for CONTROL PRE, POS, PREPOS, without difference (p>0.05). In conclusion, energy-protein supplementation of Nellore primiparous cows raised in extensive systems under tropical conditions, before and after parturition, reduces days to uterine involution and calving interval. ; La reproducción está asociada a la rentabilidad de los rebaños vacunos, que afecta al nivel de productividad y está influenciada por el nivel nutricional. El objetivo de este estudio fue evaluar el efecto de la suplementación proteica y energética, antes y después del parto, sobre las variables reproductivas de vacas primíparas Nellore criadas extensivamente en la sabana tropical brasileña. Ochenta novillas preñadas con parto estimado para un período de 45 días durante la estación seca fueron divididas al azar en cuatro tratamientos: CONTROL, recibieron una mezcla de sales minerales y urea ...