OBJECTIVE: To compare within the framework of a novel pharmacopsychometric triangle, augmentation treatment with bupropion vs. buspirone in the acute therapy of major depression in the STAR*D study. The triangle provides a composite view in three domains of antidepressive activity, side effects, and quality of life. METHOD: Within the pharmacopsychometric triangle, the short six-item subscales of the Hamilton Depression Scale (HAM-D(17)) and of the Inventory of Depressive Symptomatology (IDS-C(30)), referred to as HAM-D(6) and IDS-C(6), were focussed on pure antidepressive effect. Side-effects (tolerable vs. intolerable) and quality of life were measured using patient-administered questionnaires. A modified intention to treat sample was used. RESULTS: Within the pharmacopsychometric triangle, bupropion-SR (sustained release) was superior to buspirone when augmented to the current citalopram treatment. Thus, in the domain of pure antidepressive effect, bupropion-SR was superior (P = 0.05) on the HAM-D(6), IDS-C(6), and IDS-C(30), but not on the HAM-D(17). In the domain of side effects, the total scores on the Patient Rated Inventory of Side Effects (PRISE) were reduced significantly more by bupropion-SR than by buspirone (P = 0.03). In the domain of quality of life, the total scores on the Quality of Life Enjoyment and Satisfaction Questionnaire (QLES-Q) showed a trend (P = 0.10) from baseline to endpoint of a superiority for bupropion-SR compared with buspirone. CONCLUSION: In all domains of the pharmacopsychometric triangle, bupropion-SR was superior to buspirone as augmentation therapy in depressed outpatients not responding to citalopram.