2.1.1.17 The effects of (90)Y-daclizumab on the developing human fetus are unknown. Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, while receiving treatment and for 4 months after undergoing ASCT. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately.