A previous study suggested that under tropical conditions, Holstein cows with a high percentage of black color in their hair coats have larger productive lives than similar animals with a predominantly white coat color. Because the slick-haired (SLICK) Puerto Rican Holstein cows are better adapted to such environmental conditions than their wild type-haired (WT) counterparts, questions about other possible adaptations besides a shorter hair coat remain. In this regard, visual observations from our group suggested that SLICK cows present highly black-colored coats. Thus, the aim of this study was to quantify and compare the proportion of black and white colors in the coats between 18 SLICK and 53 WT lactating Puerto Rican Holstein cows. Cows were obtained from Lajas Agricultural Experiment Station of the University of Puerto Rico. Photos were taken from the left and right sides of each cow, close to a board of 43.18 cm in length for scaling purposes. Images were analyzed with ImageJ software (v 1.31) to determine the total area, as well as the black and white-colored spots areas on each side. These dimensions were used to calculate the respective black and white percentages. Data were analyzed using the GLIMMIX procedure in SAS. When taking into consideration the 71 evaluated cows, no differences were observed between the left and right sides for black (P = 0.9570) or white (P = 0.3324) colors; thus, sides were averaged for further analysis. Similarly, no differences were detected in the proportion of colors between SLICK and WT cows in both, white (27.68 ± 21.81 vs. 28.59 ± 22.51%, respectively; P = 0.8760) and black percentages (71.18 ± 21.51 vs. 71.09 ± 22.59%, respectively; P = 0.9877). In fact, both SLICK and WT cows showed a greater percentage of black relative to white (71.11 ± 22.27 vs. 28.35 ± 22.29%, respectively; P < 0.0001). Probably, after living in Puerto Rico for multiple generations, this characteristic has been achieved by both hair coat groups as a possible adaptation to withstand tropical weather conditions. Greater pigmentation may protect against chronic solar exposure.