Abstract: Soil isopod Phyloscia javanensis was studied for their reproductive biology in relation to soil nutrients. Isopods were acclimatized to laboratory conditions and reared in different nutrient mediums and their sex ratio, breeding cycle, clutch size and intersexuality were studied. It was found that sex ratio of this isopod depends on the nutrient composition, especially the pH and organic carbon content of the soil. The amount of nitrogen and phosphorous in the media determines the ovigerous females. Low amount of these two factors in the soil reduces egg development. Similarly the incidence of intersex formation also increases with increasing the amount of nitrogen and phosphorous in the soil. Thus it was revealed that availability of nutrients in the soil has great influence in the reproductive behavior of soil isopods.