To gain further insight into the mechanism of cell photostimulation by laser light, both RNA and protein synthesis were measured in mitochondria irradiated with the low power continuous wave He-Ne laser (Energy dose: 5 Joules/cm2). Following mitochondrial irradiation, both the rate and amount of incorporation of alpha-[32P]UTP and L-[35S]methionine, used to monitor RNA and protein synthesis respectively, proved to increase. Electrophoretic analysis made of the synthesis products clearly shows that He-Ne laser irradiation stimulates the synthesis of all mitochondrial transcription and translation products.