Ideally, immunosuppressive drugs would not be necessary in pregnancy. However, in connective tissue disease (especially systemic lupus erythematosus, SLE) vasculitis, and sometimes antiphospholipid antibody syndrome, their use is necessary both to protect the health of the mother and to insure the success of the pregnancy. The more commonly used drugs will be reviewed, with an emphasis on human data, when available. Methotrexate and leflunamide will not be considered, for they should never be used in pregnancy.