in this study whose object was to invest the ef-fects of nitrogen mustard in the level of LD5o and LDloo on nonmalignant tissues 30 rats were used. The effects of nitrogen mustard which was giyen int-raperitoneally to pregnant rats were investigated with light microscope. In the liver degenerative defects which increased with increasing dose, in the spleen white pulp orga-nization defects, in the kidney focal bleedings and in the peripheric blood smear leucopenie were detected. After procces it was observed that embrios were re-sorbed. It was emphasised that in the obligation of the use of nitrogen mustard in pregnants the toxic ef-fects should be taken care.