Two dose-levels of nefopam hydrochloride (i.e. 30 mg and 60 mg) were compared with two dose-levels of aspirin (i.e. 300 mg and 600 mg) and placebo in 125 male patients having pain associated with muscle disorders. Drugs were given as a single dose and pain intensity and side-effects monitored at thirty minutes and then hourly for four hours. Time-course action of the drugs revealed that aspirin 300 mg failed to achieve statistically significant analgesia at any post-treatment observation, whereas nefopam 60 mg was significantly better than placebo (p less than 0-05) at one and three hours in terms of pain intensity and at one hour in terms of pain intensity difference scores. Aspirin 600 mg was significantly different from placebo (p less than 0-05) at all hourly observations for both efficacy parameters, as was nefopam 30 mg (p less than 0-01). Summation of pain intensity difference scores showed aspirin 600 mg and nefopam 30 mg to be significantly different from placebo at the 0.025 and 0.005 levels respectively.