Mean GDS score was significantly decreased from 7.98 1 3.58 to 6.94 1 3.19 in the laughter therapy group after laughter therapy (P = 0.027). There was, on the contrary, no significant change of mean GDS scores in the control group before and after laughter therapy (from 8.08 1 3.96 to 8.43 1 3.44, P = 0.422). ANCOVA, controlling for pre-experimental GDS scores and other variables, showed statistical significance in the effect of laughter therapy on GDS (P = 0.011).