Subclinical ketosis is usually associated with negative energy balance in early lactation. The use of medium-chain fatty acids (MCFA) during the periparturient period can alleviate the negative energy balance and improve animal health. The objective of this study was to evaluate 30 F₁ Gir × Holstein lactating dairy cows for milk production and composition when supplemented with MCFA during the periparturient period. Diets were formulated according to the NRC (2001) model and contained 50% forage as corn silage and chopped sugar cane. Concentrate was based on ground corn, soybean meal, citrus pulp and minerals in 2 treatments: (1) No addition of MCFA (0FA) and (2) Addition of 40 g of MCFA (40FA, 0.186% of DM) as Toplac Rumacel (Nutrifarma, Taio, PR, Brazil). The experiment was a completely randomized design and cows were supplemented with MCFA during the periparturient period (from 21 d before parturition until 21 d after). Analyses of milk yield and composition were done weekly and collections were made on d 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 after parturition for each cow. Data were analyzed using the MIXED procedure of SAS and means were compared using the Tukey adjustment with significance declared as P < 0.05. Milk yield was higher for cows on 40FA (26.97 kg/d) when compared with cows on 0FA (25.50 kg/d, P < 0.05), but this trend only happened from 35 d after parturition until 70 d. Milk fat and protein yields were not different between treatments and days sampled. Somatic cell count was lower (64,260 cells/mL) for cows on treatment 40FA compared with 0FA (98,800 cells/mL, P < 0.05) suggesting that MCFA can improve mammary health. Results of this study suggest that supplementation of MCFA improved milk production and composition of F1 Gir x Holstein cows when compared with non-supplemented cows.