Background and aim: Unstable angina, a common serious clinical entity, is associated with a high rate of complications. The aim of our study was to evaluate treatment costs of patients with uncomplicated and complicated follow-up in order to evaluate the economic consequences of new therapeutic strategies, like the introduction of GPIIb/IIIa blockers at our hospital. Methodology: All 103 patients who were admitted to the medical intensive-care unit of Johann Wolfgang Goethe-University Hospital, Frankfurt am Main between March 2, 1992 and October 31, 1997 for unstable angina of Braunwald class III B were enrolled in the study. Clinical events were the occurrence of refractory ischemia, nontransmural or transmural myocardial infarction or cardiac death. The following were documented: duration of treatment in the ICU and in the general ward, cardiac catheterizations, balloon angioplasties (PTCA), and bypass operations. Treatment costs were calculated on the basis of daily rates, flat rates, and special fees. Results: Following successful primary treatment, a clinical event occurred in 48 of the 103 patients, recurrent refractory ischemia in 34 patients, nontransmural infarction in eight patients, transmural infarction in three patients, and death in four patients. Patients with events were significantly less likely to have had a history of PTCA (38 % vs 60 %, p < 0.05) and were significantly less likely to be undergoing long-term treatment with aspirin (63 % vs 80%, p < 0.05). Other sociodemographic data as well as the initial treatment strategies were comparable. The occurrence of a complication significantly prolonged the duration of treatment in the ICU from 2.6 days (95%-CI [2.1; 3.0]) to 3.6 days (95%-CI [3.1; 4.1]) and the total duration of treatment from 7.0 days (95%-CI [5.7; 8.4]) to 12.8 days (95%-CI [9.6; 16.1]). The total treatment costs rose accordingly from DM 14,360 (95%-CI [12,360; 16,360]) to DM 26,690 (95%-CI[23,150; 30,240]). Conclusion: The data show that ischemic complications following successful primary treatment of unstable angina constitute a common problem. Such complications are associated with significantly more intensive treatment and significantly longer hospitalization times, resulting in a near doubling of treatment costs.