Triethylenethiophosphoramide ( thioTEPA) and mechlorethamine (nitrogen mustard) are used at the time of operation for cancer to discourage the local and distant implantation of the cancer cells in the body. If these cytotoxic drugs are capable of destroying the malignant cells, it is logical to question whether they might also affect the young and proliferating cells of a healing wound. In a previous report1 we showed experimentally that mechlorethamine interfered with the healing of wounds and reduced their tensile strength. Mechlorethamine also caused weight loss in animals (Fig. 1). We were, however, unable to determine whether reduction of tensile strength was a direct result of mechlorethamine on the healing wound or secondary to malnutrition (as manifested by loss of weight). In the present study we have determined the effect of thio-TEPA on the healing of abdominal wounds in rats. The results suggest that thio-TEPA, in contrast with mechlorethamine, does not