Highly interruptive clinical environments may cause work stress and suboptimal clinical care. This study features an intervention to reduce workflow interruptions by re-designing work and organizational practices in hospital physicians providing ward coverage. A prospective, controlled intervention was conducted in two surgical and two internal wards. The intervention was based on physician quality circles - a participative technique to involve employees in the development of solutions to overcome work-related stressors. Outcome measures were the frequency of observed workflow interruptions. Workflow interruptions by fellow physicians and nursing staff were significantly lower after the intervention. However, a similar decrease was also observed in control units. Additional interviews to explore process-related factors suggested that there might have been spill-over effects in the sense that solutions were not strictly confined to the intervention group. Recommendations for further research on the effectiveness and consequences of such interventions for professional communication and patient safety are discussed.