OBJECTIVE: The aim of this study was to examine the cutaneous vascular and sudomotor responses to combined moderate passive heat stress and normobaric hypoxia. METHOD: Thirteen healthy young males, dressed in a water-perfused suit, underwent passive heating (Δcore temperature ~0.7°C) twice (Normoxia; 20.9% O2 and Hypoxia; 13% O2 ). Chest and forearm skin blood flow (SkBF; laser-Doppler flux) and sweat rate (SR; capacitance hygrometry), core (intestinal pill), and skin temperatures, were recorded. RESULTS: Hypoxia reduced baseline oxygen saturation (98±1 vs 89±6%, P<.001) and elevated chest (P=.03) and forearm SkBF (P=.03), and HR (64±9 vs 69±8 beats.min-1 , P<.01). During heating, mean body temperature (T¯BODY) thresholds for SkBF (P=.41) and SR (P=.28) elevations were not different between trials. The SkBF: T¯BODY linear sensitivity during the initial phase of heating was lower at the chest (P=.035) but not different at the forearm (P=.17) during hypoxia. With increasing levels of heating chest SkBF was not different (P=.55) but forearm SkBF was lower (P<.01) during hypoxia. Chest (P=.85) and forearm (P=.79) SR: T¯BODY linear sensitivities were not different between trials. CONCLUSION: While sudomotor responses and the initiation of cutaneous blood flow elevations are unaffected, hypoxia differentially effects regional SkBF responses during moderate passive heating.