Interactions between exposure to xenobiotics and disease can occur during pregnancy. Few data are available on the consequences of such interactions on developmental parameters. In this study, we investigated potential interactions between murine cytomegalovirus (MCMV), which induces embryolethality, and sodium salicylate, a known teratogen. MCMV administered on Day 12 was embryotoxic over a broad range of doses from 2 x 10(3) to 2 x 10(6) plaque-forming units, and also decreased postnatal weight gain. MCMV administration on Day 8 of gestation caused significant prenatal mortality regardless of salicylate exposure. Salicylate did not cause fetal mortality or malformations at either 500 or 750 mg kg-1 day-1 on Days 9 and 10 of gestation. No evidence of synergistic effects of MCMV and salicylate on embryo/fetal development was seen.