Objective : The effects of Indium-Gallium-Aluminium-Phosphide(InGaAlP) laser transcutaneous irradiation on heart rate variability(HRV) in healthy adults are investigated with power spectrum analysis(PSA) of HRV. Methods : The control group consisted of 20 healthy volunteers (10 men, 10 women). The experiment was divided into 5 different periods, the pre-1st laser period(10 minutes), the 1st laser period(30 minutes), the post-1st laser period(5 minutes), the 2nd laser period( 30 minutes) and the post-2nd laser period(30 minutes). HRV was measured for 5 minutes at the pre-1 st laser period, the post-l st laser period and the post-2nd laser period. The laser period is the period in which InGaAlP laser transcutaneous Irradiation treatment occurs. Results : 1. SDNN of volunteers at post-1st laser period and post-2nd laser period significantly increased compared with that of the pre- 1 st laser period. 2, Ln(VLF) at post-I st laser period significantly increased compared with that of pre-1st laser period, while Ln(HF) at post-2nd laser period significantly decreased compared with those of pre- I st laser period and post-1st laser period, 3. Ln(TP) at post-1st laser period and post-2nd laser period significantly increased compared with that of pre-1st laser period, 4, LF/HF Ratio at post-2nd laser period significantly increased compared with those of pre-1st laser period and post-1st laser period. But the other variables did not significantly change. Conclusions : The results suggest that InGaAlp laser transcutaneous Irradiation in healthy adults is associated with the autonomic nervous systems. Further study is needed for investigating the effects of laser irradiation on autonomic nervous systems.