The rat acute oral LD50 value of PSCl3 is 750 mg per kg body weight. A rat 90-day oral feeding study at dose levels of 7.5 mg (P1) and 37.5 mg (P5) per kg resulted in increased body weight gain. Other responses inconsistently varied between dose levels. At 7.5 mg kg-1, a trend towards enhancement of relative weight of liver, spleen, kidney and adrenals was noted; at 37.5 mg kg-1, decreasing relative spleen and adrenal weights were observed. The most of the hematological and biochemical changes in blood serum cannot be believed to be transitory adaptive changes, but valid toxic effects. On the other hand, there are some indicators that suggest a possible trophic effect of this compound. However, the reversible dystrophic changes in liver, as well as the histochemical and histoenzymical results, require us to take into account that inactive chronic hepatitis could be reactivated by further toxic insult. A teratology study demonstrated increased number, body weight and length of fetuses, without apparent pathological events (tumors, external malformations). A mutagenicity test performed on rat femoral bone marrow after 30-days feeding of 37.5 mg kg-1 did not indicate any significant change in the incidence of chromosomal aberrations, compared with the control group. The recommended maximum allowable concentration in the working zone for thiophosphoryl chloride in air was set at 3 mg m-3.