The study was conducted to observe the effect of seasons on thermoregulation responses. A total of 100 cows including 50 Sahiwal and 50 Karan Fries cows were selected from Livestock Research Centre of ICAR-National Dairy Research Institute, Karnal, India. The study was conducted during winter (THI=49.67±1.18), spring (THI=64.65±0.41) and summer (THI=87.28±1.26) seasons. Changes in RR, RT and HTC were observed in different seasons in Sahiwal and Karan Fries cows. In Sahiwal cows RT (°C) during winter, spring and summer were 37.300±0.095c, 38.178±0.095b and 38.810±0.095a respectively whereas RT (°C) in Karan Fries were 37.492±0.115c, 38.398±0.115b and 39.186±0.115a during winter, spring and summer respectively. RR (breaths min-1) in Sahiwal cows during winter, spring and summer were 15.738±0.795c, 18.158±0.795b and 29.818±0.795a respectively whereas RR in Karan Fries during winter, spring and summer were 15.779±1.136c, 22.979±1.136b and 47.299±1.136a respectively. The magnitude of increase in RR, RT and HTC were found to be higher during summer compared to other seasons in both Sahiwal and Karan Fries cattle. It was observed that Sahiwal cows are less sensitive and are better able to regulate body temperature in response to heat stress than Karan Fries cows.