LBD-007, a newly developed recombinant human interferon alphaA, was at dose levels of 0.3 $ imes$$10^6$ , 6 $ imes$ $10^6$ and 12 $ imes$ $10^6$ IU/kg/day administered subcutaneously to pregnant New Zealand White rabbits during the organogenetic period. Cyclophosphamide was used as a positive control. All pregnant females were subjected to the caesarean section on day 28 of pregnancy. Effect of test substance on dams and embryonal development of fetuses were examined. 1. No treatment-related changes in clinical signs, food consuption, body weight and necropsy findings of dams were observed.