Approximately 75% of the 181,000 breast cancer patients newly diagnosed in 1992 will survive for at least 5 yr, but survival often depends on receiving adjuvant chemotherapy. We determined that mood variables and attitude toward cancer could predict compliance with IV-administered chemotherapy. The participants were seventy-four women diagnosed with primary breast cancer receiving treatment at a state-supported medical center in one of three southeastern metropolitan areas in the U.S. Most patients were members of minority and lower socioeconomic groups. The design was prospective in the sense that mood and attitude variables were assessed before determination of compliance. Two psychological instruments were used in this study, the Mental Adjustment to Cancer (MAC) Scale and the Affects Balance Scale (ABS). Patients who kept fewer than 85% of their appointments were classified as noncompliant; those keeping 85% or more were classified as compliant. Sixty-three percent of the patients for whom the compliance information was complete were classified as compliant; 37% were noncompliant; and four patients were not included in the analysis because their records were incomplete. The discriminant function was able to correctly classify 86% of the patients according to chemotherapy compliance, a 36% improvement over the chance level. High scores on MAC Fighting Spirit and ABS Anxiety, Depression, and Vigor scales were associated with greater adherence to a chemotherapy regimen. High scores on ABS Guilt and Hostility scales predicted lower levels of compliance.