Orthodichlorobenzene (ODCB) and paradichlorobenzene (PDCB) were evaluated for teratogenic potential in rats (ODCB only) and rabbits. Groups of bred rats and inseminated rabbits were exposed to 0, 100, 200, or 400 ppm of ODCB; groups of inseminated rabbits were exposed to 0, 100, 300, or 800 ppm of PDCB. Animals were exposed for 6 hr/day on Days 6 through 15 (rats) or 6 through 18 (rabbits) of gestation. Maternal toxicity, as evidenced by a significant decrease in body weight gain, was observed in all groups of ODCB-exposed rats and liver weight was significantly increased in the 400-ppm ODCB-exposed group. Slight maternal toxicity was observed in groups of rabbits exposed to 400 ppm ODCB or 800 ppm PDCB as indicated by significantly decreased body weight gain during the first 3 days of exposure. Inhalation of up to 400 ppm of ODCB was not teratogenic or fetotoxic in rats, and neither ODCB nor PDCB was teratogenic or fetotoxic in rabbits at exposure levels up to 400 or 800 ppm, respectively.