In the context of chronic physical illness, such as breast cancer, depression is associated with increased morbidity, longer periods of hospitalization, and greater overall disability. Prompt diagnosis and effective treatment is. therefore, essential. Several small studies have established the efficacy of tricyclic antidepressants (TCAs) in this setting, and the selective serotonin reuptake inhibitors (SSRIs) would appear to be an alternative therapeutic option because of their established efficacy and better tolerability profile. This was a multicenter. double-blind, parallel-group study in which 179 women with breast cancer were randomized to treatment with either the SSRI paroxetine (20-40 mg/day), or the TCA, amitriptyline (75-150 mg/day). After 8-weeks treatment, depressive symptomatology had improved markedly and to a similar extent in both groups on the Montgomery Asberg Depression Rating Scale. Clinical global impression (CGI) Global improvement and Patient global evaluation scales indicated that patients were minimally to much improved at study endpoint: a change from moderately/mildly ill to borderline ill on the CGI severity of Illness scale. A steady improvement in quality of life was also observed in both groups. There were no clinically significant differences between the groups. In total, 47 (53.4%) patients in the paroxetine group and 53 (59.6%) patients in the amitriptyline group had adverse experiences, the most common of which were the well-recognized side-effects of the antidepressant medications or chemotherapy. Anticholinergic effects were almost twice as frequent in the amitriptyline group (19.1%) compared with paroxetine (11.4%). This study has demonstrated that paroxetine is a suitable alternative to amitriptyline for the treatment of depression in patients with breast cancer.