Previous studies suggest that females experience less vascular occlusion than males when generating the same relative contractile force. This study examined forearm blood flow (FBF) in females and males during isometric handgrip exercise requiring the same relative force. Thirty-eight subjects (20 female and 18 male, 22.8 ± 0.6 yrs old, (mean ± SE)) performed low- and moderate-force handgrip exercise on two occasions. Subjects performed 5 maximum voluntary contractions (MVC) prior to exercise to determine 20% and 50% MVC target forces. Time to task failure (TTF) was determined when the subject could not maintain force within 5% of the target force. Mean blood velocity was measured in the brachial artery using Doppler ultrasonography. Arterial diameter was measured at rest and used to calculate absolute forearm blood flow (FBFa ;ml/min) and relative forearm blood flow (FBFr ;ml/min/100ml). Females enerated less (p<0.05) absolute maximal force (208 ± 10 N) compared to males (357 ± 17 N). The TTF was longer (p<0.05) at 20% MVC for females (349 ± 32 s) than for males (230 ± 23 s) but no difference between the sexes were observed at 50% MVC (females, 69 ± 5 s; males, 71 ± 8 s). FBFa and FBFr increased (p<0.05) from rest to task failure in both females and males during 20% and 50% MVC trials. FBFr was greater in females compared to males at 30% TTF during 50% MVC. At exercise durations 60% of TTF, FBFa was lower (p<0.05) in females than males during handgrip at 20% MVC. In spite of the longer exercise duration for females at the lower contraction intensity, FBFr was similar between the sexes suggesting that muscle perfusion is matched to the exercising muscle mass independent of sex.