Purpose of present work was to evaluate the effect of supplementation of rumen-protected vitamins (choline, riboflavin and folic acid) on incidence and appearance metabolic diseases. Dairy cows (n = 105), on the transition period (fresh and challenged cows). Cows were randomly allotted from May to August into 2 groups: 1) Control cows (cows receiving the regular total-mixed ration without vitamin supplementation; TMR), and 2) RPV-cows (cows receiving a supplement containing rumen-protected vitamins; i.e., 50 g/cow/day). Five blood samplings were performed to determine incidence of metabolic disorders and/or postpartum diseases (d 0, 19, 30, 50, and 80 after R-PV supplementation). Three periparturient diseases were monitored: retained fetal membranes, metritis, and ketosis, defined as follows: (1) retained-fetal membranes (RFM), was considered when fetal membranes were not expelled 12 h after parturition; 2) metritis (M) was diagnosed when cows presented a blood-purulent vaginal discharge at 7 d after parturition; (3) ketosis: mount of β-hydroxybutyrate was determined though evaluation of a blood sample using reactive bands for ketone bodies (Abbott, Precision Xtra), and using a Ketometer (Ketometer Precision Xtra). Data were analyzed using a 2-independent samples comparison analysis, using a 2 × 2 contingency table (considering year and treatment). Supplementation of rumen-protected vitamins (RPV: choline, riboflavin and folic acid), during the transition period of dairy cows, reduced incidence of retained fetal membranes from 52.24 to 12.30%; incidence of ketosis from 29.52 to 6.67% and incidence of metritis from 79.05 to 15.24% (P < 0.05). In conclusion, under present study conditions, supplementation 50 g/cow/d of rumen-protected vitamins (choline, riboflavin and folic acid), during the transition period, significantly reduced incidence of retained fetal membranes, metritis and ketosis, in heat-stressed dairy cows at northern Mexico (La Laguna dairy region).