The genetic effect of three stocks of D. melanogaster, C. S., Base, and bw-st/bw-st were studied with irradiation from He-Ne, nitrogen and argon ion lasers. Experimental results show that when the radiation dosages of He-Ne laser, nitrogen laser and argon ion laser amounted to 32J/cm3, 0.75J/cm2 and 196J/cm2, respectively, genetic effects of recessive lethal mutation and translocation have not been observedyet.