We investigated the combined effect of resistance exercise and arginine ingestion on spontaneous growth hormone (GH) release. Eight healthy males were studied randomly on 4 occasions (placebo, arginine (Arg), placebo+exercise (Ex), arginine + exercise (Arg+Ex). Subjects had blood sampled every 10 minutes for 3.5h. After baseline sampling (30 min), subjects ingested 7g of Arg or placebo (blinded, randomly assigned). On the exercise days, the subject performed 3 sets of 9 exercise, 10 reps at 80% 1RM. Resting GH concentrations were similar on each study day. Integrated GH area under the curve was significantly higher on the Ex day (508.7 ± 169.6 min^.ng/ml, P<0.05) than on any of the other study days. Arg+Ex (260.5 ± 76.8 min^.ng/ml) resulted in a greater response than the placebo day but not significantly greater than the Arg day. The GH half-life and half duration were not influenced by the stimulus administered. The GH secretory burst mass was larger, but not significantly, on the Arg, Ex and Arg+Ex than the placebo day. Endogenous GH production rate (Ex> Arg+Ex> Arg> placebo) was greater on the Ex and Arg+Ex day than on the placebo day (P<0.05) but there were no differences between the Ex and Arg+Ex day. Oral arginine alone (7g) stimulated GH release but a greater GH response was seen with Ex alone. The combined effect of arginine prior to exercise attenuates the GH response. Autonegative feedback possibly causes a refractory period that when the two stimuli are presented that there will be suppression of the somatotrope.