BACKGROUND Bedside teaching encounters on hospital wards offer medical students opportunities to learn key medical and interpersonal skills. Although many aspects of bedside teaching have been studied, not much is known about the selection process used by medical teachers to find patients for these encounters. Patient selection could have a substantial impact on medical students' clinical experiences. Therefore, we studied the ways in which medical teachers select patients for bedside teaching and tried to determine the factors that affect patient selection. METHODS Using a qualitative research approach, we interviewed 15 teachers from three departments within the Medical Faculty at Hamburg University on how they choose patients for bedside teaching encounters. We extracted selection criteria from the transcripts of the audio-recorded interviews and identified other factors that influenced selection. RESULTS One main category and two minor categories of factors relevant to patient selection were identified: educational; bio-psycho-social, and structural. Medical teachers look primarily for patients who have diseases that fit their conceptions of the learning objectives of the lessons in question. The two minor categories influence their choice of patients in different ways. By finding a balance between these categories, they decide which patients are eligible for participation. As a result of these selection criteria, some patients are more likely to become involved in clinical teaching, whereas others may be omitted. CONCLUSIONS Patient selection for bedside teaching is based on several criteria. Non-representative patient selection may narrow the learning experiences of medical students. Curriculum planners need to be aware that specific aspects of medical care may be neglected as a result of the exclusion of some patients. Teacher training and additional teaching formats should be provided to ensure that these are covered.