The goal of this study was to investigate the effects of RPMet supplementation during transition on milk yield and composition, diseases’ prevalence and culling. One hundred and 66 Holstein animals, 58 nulliparous and 108 multiparous cows, were blocked by parity and expected calving date and randomly allocated in 2 treatments: Control and RPMet. Cows were individually fed and the RPMet group received a top-dressed methionine product (Smartamine, Adisseo Inc.) during 21 d prepartum (8 g/cow/d) and 16 d postpartum (15 g/cow/d), maintaining a lysine/methionine ratio of 2.81/1. After 16 d postpartum all animals received RPMet (15 g/cow/d). Daily milk yield (kg) was recorded as an average of the first 60 DIM. Milk samples were collected in the first and second lactation weeks to determine its composition. Mortality and morbidity, considered as the occurrence of one or more of the following diseases: retained placenta, ketosis, mastitis, hypocalcemia, metritis, and pneumonia, were recorded during the first 60 DIM. Milk yield and its composition were analyzed using MIXED procedure, with a model containing the effects of block, treatment, time, and treatment × time interaction as fixed effects and cow within treatment as a random effect, while binary data for morbidity and culling were analyzed using GLIMMIX procedure of SAS. Milk yield did not differ (P = 0.87; SEM = 1.14) between treatments, as well as energy-corrected milk (P = 0.47; SEM = 0.89). There was a trend of RPMet cows to produce higher (P = 0.07; SEM = 0.12) milk fat content, 4.40 vs. 4.07%, respectively. Rumen-protected methionine animals did not show higher milk protein (3.46 vs. 3.38%; SEM = 0.04; P = 0.20) or casein (2.73 vs. 2.65%; SEM = 0.04; P = 0.19) contents. Other milk components were similar (P > 0.10) between treatments. In addition, morbidity showed similar (P = 0.87; EPM = 0.05) rates, while culling was much higher for control animals than for RPMet cows (12.05% vs. 2.41%; SEM = 0.02; P = 0.03). Overall, results suggest that RPMet can improve milk fat content and decrease involuntary culling of early lactation dairy cows.