The purpose of this investigation was to study the effects of an acute bout of aerobic exercise on state anxiety of women while controlling for iron status (hemoglobin and serum ferritin). Participants were 24 active women, ages 18-20 years (n=12) and 35-45 years (n=12). In addition to a nonexercise control condition, participants completed one exercise bout at 60% maximal oxygen uptake (V[O.sub.2]max) and one at 80% V[O.sub.2]max. Each exercise session consisted of a 33-min bout in which participants exercised at their target intensities for a 20-min segment. Immediately before each exercise trial, participants were given the Spielberger State Anxiety Inventory (SAI). The SAI was again administered immediately following the exercise session and at 30, 60, and 90 min postexercise. Data were analyzed using an Age x Intensity x Time (2 x 3 x 5) repeated measures analysis of covariance (ANCOVA) with iron status serving as the covariate. The ANCOVA on state anxiety yielded significant effects for time (p [is less than] .0001,[[eta].sup.2.sub.p]=.48), the Intensity x Time interaction (p =.0006, [[eta].sup.2.sub.p]=.19), and the Intensity x Age interaction (p=.04, [[eta].sup.2.sub.p]=.15). All three exercise conditions (including control) showed a decline in state anxiety across time, but the 80% V[O.sub.2]max condition showed a sharper decline. Intensity of exercise conditions did not differ in state anxiety at baseline or immediately after exercise, but a difference favoring the 80% V[O.sub.2]max condition over the control condition emerged at 30 min postexercise. After controlling for iron status, older women who exercised at 80% V[O.sub.2]max exhibited lower SAI scores compared to the control condition.