Thirty-two female students participated in a single-session experiment during which they carried out two 8-min trials of high-intensity exercise and two 8-min trials of low-intensity exercise. One high- and one low-exercise trial were accompanied by music; the other two trials were accompanied by metronome. Mood was assessed with a modification of the Profile of Mood States before and immediately after each trial. The purpose of the experiment was disguised to reduce the influence of subject expectations on mood responses. Participants were divided into fit and unfit groups based on heart rate responses during high-exercise trials. Overall, high-intensity exercise led to increases in tension/anxiety and fatigue, whereas positive mood changes (vigor and exhilaration) were seen following low-intensity exercise only. No group differences in mood responses were observed. Explanations of these results are considered in light of other literature concerning the acute effects of exercise on mood.