The slick hair phenotype is associated with enhanced thermoregulation in Holstein cows; however, no such data are available in slick-haired Jersey cows. The relationship between hair coat type (phenotypically determined), vaginal temperature (VT; as an index of core body temperature), respiration rate (RR), and thermal humidity index (THI) was evaluated in 10 Puerto Rican Jersey cows [5 wild type-haired (WT; 111.2 ± 0.8 d in milk (DIM); 1.2 lactations) and 5 slick-haired (SLICK; 171.6 ± 1.5 DIM; 1.2 lactations)]. Cows were exposed to solar radiation from 1030 to 1130 h and to artificial shade from 1130 to 1030 h during 5 consecutive days. Data loggers recorded VT (TidbiT v2), air temperature, and relative humidity (HOBO Pro v2) every 5 min and the THI was determined. Daily THI ranged from 63.47 – 81.77. The RR was recorded at 0600, 0800, 0900, 1000, 1100, 1200, 1300, 1400, and 1500 h daily. Data were analyzed using the GLIMMIX and CORR procedures of SAS. There were no differences in VT between hair type groups either under sun or shade exposure (P = 0.43). From 1030 to 1130 h (direct solar radiation exposure) mean VT values of 39.08 ± 0.02 and 39.26 ± 0.02°C were observed in SLICK and WT cows, respectively. During the 1130–1030 h (shade period), SLICK and WT cows presented mean VT values of 38.80 ± 0.01 and 38.89 ± 0.01°C, respectively. However, SLICK cows presented lower RR than their WT counterparts (P = 0.004). Mean daily RR values of 56.0 ± 5.2 and 77.6 ± 5.0 breaths per minute were observed in the SLICK and the WT cows, respectively. Correlation coefficients of 0.68 (P < 0.0001) and 0.47 (P < 0.0001) were observed between the VT and the RR in WT and SLICK cows, respectively. However, VT was less associated with THI in WT than in SLICK cows [r = 0.24 (P < 0.0001) and r = 0.50 (P < 0.0001), respectively]. In conclusion, slick-haired Jersey cows were able to maintain similar vaginal temperature than their wild type-haired counterparts, but with a lower respiration rate. These findings suggest that wild type-haired Jersey cows’ body temperature regulation requires greater heat dissipation through evaporation than their slick-haired counterparts.