AIM: The aim of this study was to analyze the short-term effect of testosterone (T) administration on muscle strength and neuromuscular system properties in hypogonadal males. METHODS: Seven hypogonadal males assumed in random order either 80 mg of T gel or a placebo preparation gel (PLA) once a day for 4 consecutive days. Before, 4 and 96 hours after T or PLA gel administration, maximal isometric (MVC) and isokinetic (15, 30, 60, 120, 180 and 240°/s) torque of the elbow flexors (EF) were assessed. Single twitches were evoked before and after a fatiguing task. Average muscle fibres conduction velocity (MFCV) of the EMG from the biceps brachii muscle was evaluated. RESULTS: EF maximal torque seems not to be acutely influenced by T during isometric and isokinetic tests. MFCV estimated during these voluntary tests, showed a similar trend in PLA and T conditions without any significant differences between pre and post administration. Four and 96 h after T administration, MFCV of the evoked twitches was decreased with respect to the baseline condition while it remained unchanged after PLA. CONCLUSION: Taken together these results suggest that in hypogonadal men a short-term T gel administration may induce a depression in muscle excitability, as already demonstrated in animals. We could hypothesize that MFCV assessment during evoked twitches may be useful to monitor neuromuscular changes during T substitution in hypogonadal individuals.