Objectives. To assess the impact of process analyses and modifications on inappropriate hospital use. Design. Pre-post comparison of inappropriate hospital use after process modifications. Setting. The Department of Internal Medicine of the Geneva University Hospitals, Switzerland. Participants. A random sample of 498 patients. Interventions. Two processes of care (i.e. non-urgent admissions and transfer to a rehabilitation hospital), which influenced inappropriate hospital use, were identified and modified. The impact of these modifications was then assessed. Main outcome measures. The proportion of inappropriate hospital admissions and inappropriate hospital days. Results. As a baseline assessment before quality improvement interventions, the appropriateness of hospital use (admissions and hospital days) was evaluated using the Appropriateness Evaluation Protocol (AEP) in a sample of 500 patients (5665 days). After modification of the two processes through a quality improvement program, inappropriate hospital use was reassessed in a sample of 498 patients (6095 days). Inappropriate hospital admissions decreased from 15 to 9% (P = 0.002) and inappropriate hospital days from 28 to 25% (P = 0.12). Conclusion. Using the AEP as a criterion, the quality improvement interventions significantly reduced inappropriate hospital use due to the process of non-urgent admissions, but the reduction of inappropriate hospital days specifically attributed to the transfer to the rehabilitation hospital did not reach statistical significance.