Combination (1 : 20) of pyrimethamine (PY) and sulfamonomethoxine (SMX) was mixed with mashed feed and given to the Goettingen miniature pig during gestational days 11 - 35. Major malformations such as cleft palate and micrognathia were observed in 7 out of 1 8 newborns from 3 pregnant sows which received 3.6 mg/kg/day of PY with 72 mg/kg of SMX. Two sows of a higher dose group (7.2 mg/kg PY + 144 mg/kg SMX) showed severe anemia during the experiment and did not give a birth. No major malformation was found in 23 newborns of lower dose groups. In comparison with the previous results by PY alone, it is concluded that sulfa drug might not potentiate the teratogenic action of PY in pig .
