OBJECTIVES: To evaluate the pharmacoeconomics of hawthorn-extract treatment of CHF at stage NYHA II, a prospective 3-year observational study has been conducted since summer 1999. A cost-utility-analysis (CUA) will compare hawthorn treatment (WS 1442 as mono- or add-on-therapy) to any other treatment option. The results of two years of study conduct are presented. METHODS: Open, non-randomized observational cohort study with matched-pairs evaluation. The first cohort (Hawthorn-Cohort, HC) comprises patients receiving hawthorn-extract therapy of CHF. In the second cohort (Conventional-Cohort, CC) patients without hawthorn but any other treatment were observed. In 217 study centres 952 patients were included (HC: 588; CC: 364). A number of 116 pairs were determined as sample size necessary for evaluation. For measuring HRQL the EuroQoL-5D was used. Matching criteria were derived from demographic factors and clinical diagnosis. The perspective of the German statutory health insurance funds was applied. RESULTS: 130 pairs could be established under consideration of two-year data. Median direct costs per year for HC amounted to € 473 and for CC to € 449. This difference is not significant (p=.218). Most important cost-driving factor was drug acquisition (median HC: € 260, CC: € 293). Significantly fewer prescriptions have been detected in the HC for ACE-inhibitors, diuretics, digitalis, and beta-blockers. HRQL was improved significantly in both years over two years, the improvement was slightly better in HC; however, no significant differences could be detected. Therefore a conduct of a CUA is not yet possible. Safety and efficacy in HC have been assessed significantly better by the treating physicians. CONCLUSIONS: According to German guidelines, ACE-inhibitors are recommended as first-line therapy for CHF. The data show that in some cases this conventional therapy may be replaced by hawthorn-extract with the same or slightly better outcome. The final results of the study are expected for 2003.