Saccharomyces rosinii which was isolated from River Nile water samples (Embaba) was selected as the most potent hydrocarbon degrading yeast isolate. The cell suspension (104 CFU/ml) was subjected to different irradiation doses using low power He-Ne laser (λ=632.8nm) with varying exposure durations (1, 3 and 6 minutes). Complete degradation of the normal octane, ethyl benzene and their mixture as representative components of their families was achieved after 3 minutes (equivalent dose = 99.6 J/ cm2) of laser irradiation. The bioremediation of paraffinic and polynuclear aromatic hydrocarbon mixtures was studied using irradiated and non irradiated cell suspensions. Gas chromatographic analysis of the residual substrates indicates the degradation of 98.31% of the paraffinic hydrocarbons and 98.09 % of the polynuclear aromatic hydrocarbons after 30 hrs of incubation. These results demonstrates the superiority of the irradiated yeast isolate and supports its future use in the bioremediation programs of industrial waste water.