The objective of the present study was to evaluate milk yield and composition of dairy cows receiving saturated or unsaturated fatty acids (FA) sources during transition period and early lactation. Thirty Holstein cows were divided into 3 experimental groups in randomized complete design. The animals were randomly assigned to receive one of the following treatments: 1) control (C; without fat addition, n = 10), basal diet containing (DM basis) 2.5 g/100g of ether extract (EE) in pre and postpartum period; 2) calcium salts of saturated FA (SAT; Magnapac - Tectron Ltd., n = 10), basal diet containing (DM basis) 4.5 g/100g of EE in pre-partum and 5.5 g/100g in postpartum; 3) whole raw soybeans (UNSAT; n = 10), basal diet containing (DM basis) 4.5g/100g of EE in pre-partum and 5.5g/100g of EE in postpartum period. The animals were fed individually, and the experimental diets were fed since 35 d before the expected calving date, and provided until 90 d of lactation and were formulated to meet the nutritional requirements of each period (pre and postpartum). Milk yield was measured daily and samples for milk composition were collected weekly from the first to the 13th week of lactation. Data were analyzed using PROC MIXED of SAS 9.1, with the effect of diet, time and interaction as fixed effects, and animal as random effect. The data were analyzed by orthogonal contrasts (C vs. UNS + SAT and UNS vs. SAT). Fatty acids sources did not influence (P > 0.05) milk yield, protein and lactose (kg/d and %). The average milk yields were 30.07, 28.86, and 30.85 kg for C, UNS and SAT, respectively. Unsaturated fatty acids source reduced the FCM (28.12 Kg/d vs 33.63 kg/d) (P = 0.029), and milk fat (4.16% vs. 3.37%; 1.23 kg/d vs 0.95 kg/d) (P = 0.006) (P = 0.004) for UNS vs SAT contrast. The supplementation of dairy cows with fatty acids sources in the transition period and early lactation affected the FCM and milk fat yield and percent.