This work analyzed the impact of Chlorella vulgaris (CV) microalgae administration on some hematological parameters and thermoregulation of Boer goats subjected to heat stress. Fifteen lactating Boer goats (35 ± 1.8 kg BW) were assigned to three groups (5 goats each), control diet, C V supplemented diet (7.5 g/head/ day) and C V supplemented diet (15 g/head/ day) that were subjected to heat stress for 90 days. AT and RH% data were recorded and used in calculate the current THI. Blood samples were obtained from all goats biweekly from jugular vein. Physiological parameters were measured and recorded during the experimental days.  The results obtained showed that CV increases RBC count, HGB concentration, and HCT. Whereas RT, RR and PR decreased significantly (P < 0.05) in Boer goats. In this study, we can conclude that C V could improve some blood hematological parameters and thermoregulation of Boer goats in arid subtropical regions.