An experiment was conducted in order to evaluate the effects of microclimate and thermoregulatory responses of locally adapted ewes under monoculture or silvopastoral systems in the Brazilian semi-arid region. Eighteen sheep were distributed according to monoculture and silvopastoral systems in a randomized block design with three replications. Eighteen evaluations were carried out every two hours during the animals' stay in the pasture (6-18 h). The microclimatic characteristics measured were: ambient temperature (degrees C), black globe temperature (degrees C), wet bulb temperature (degrees C), and wind speed (m.s-1). Those variables were used to calculate relative humidity (RH, %), black globe humidity index (BGHI), and radiant heat load (RHL, w.m2). In order to evaluate thermoregulatory responses, heart rate (HR, beats.min-1), respiratory rate (RR, breaths.min-1), rectal temperature (RT, degrees C), and coat surface temperature (CST, degrees C) were assessed. There was a significant effect of interaction on BGHI, which was lower in the silvopastoral system during the interval 10-12 h, with a mean value of 93.1. Ambient temperature was lower in the silvopastoral system when compared to the monoculture (32.5 and 33.3 degrees C, respectively). In both systems, the highest RHL values were recorded during the intervals 10-12 h (659 w.m2) and 12-14 h (665 w.m2), while there was a pronounced increase in BGHI from 12 to 14 h with a mean value of 96. Regarding thermoregulatory responses, an interaction effect (treatment x period) was observed on RR, which was higher in animals in the monoculture system from 12 to 14 h, showing 91.8 breaths.min-1, while in the silvopastoral system, animals showed approximately 78.9 breaths.min-1. The silvopastoral system provided better average environmental temperature, with positive effects on BGHI and RR at times considered more stressful to the animals.