Dairy cattle in the tropics are exposed to chronic heat stress, which affect DMI, milk yield (MY), and feed efficiency (FE). Our objective was to evaluate FE between dairy cows with 2 genotypes: Slick-hair (SL) and wild-type (WT), under heat stress. SL (n = 8) and WT (n = 8) lactating cows with an average of 140 DIM, were used to evaluate FE for 60 d during April and May of 2018 in Puerto Rico (18. 027435,-67. 094955). Average THI during the experiment was 75.8 ± 0.03. Animals were fed a TMR based on Brachiaria spp. forage, soybean meal, steam flaked corn grain, brewers’ grains, and minerals. On average the TMR contained 13.9% CP, 1.4 Mcal NEL/kg, 16.5% starch, and 43.1% aNDFom. The DMI was recorded daily with a Calan Feeding System and individual milk yield per cow was recorded daily with the Afimilk system. Milk was chemically analyzed weekly. Energy corrected milk (ECM) was calculated using the formula: ECM (kg/d) = 0.25 × kg of MY + 12.2 × kg of fat yield + 7.7 × kg of protein yield. Weekly average of milk yields and DMI, and weekly pooled milk components data were analyzed using Proc Mixed of SAS using a model that included genotype (SL and WT), week and their interactions as fixed effects. For each parameter week was used as a repeated measurement with cow as the subject. When evaluating MY, there was no interaction between genotype and week (P = 0.316). There was no difference in MY between genotypes (P = 0.598). Average MY in SL cows was 20.49 ± 0.94 kg with an average of 5.5% ± 0.24 fat and 3.42% ± 0.06 protein, while average MY in WT cows was of 19.49 ± 0.88 kg with an average of 4.86% ± 0.26 fat and 3.16% ± 0.07 protein. There was no difference in protein (P = 0.233) or fat (P = 0.164) content between the genotypes. Average DMI in SL was 18.72 ± 0.38 kg and WT 19.11 ± 0.38 kg (P = 0.72). FE was determined as kg of ECM/ DMI (kg). When evaluating FE, there was no interaction between genotype and week (P = 0.316). There was no difference in FE between genotypes (P = 0.598). SL cows had an average FE of 1.22 ± 0. 05; while WT cows had an average of 1.11 ± 0.08. In this study, where SL and WT cows were exposed to high THI and a high forage TMR diet, both genotypes presented a similar FE.