BACKGROUND: Similarities and differences in physician work intensity among specialties are poorly understood but have implications for quality of care, patient safety, practice organization and management, and payment. OBJECTIVE: To determine the magnitude and important dimensions of physician work intensity for 4 specialties. RESEARCH DESIGN: Cross-sectional assessment of work intensity associated with actual patient care in the examination room or operating room. SUBJECTS: A convenience sample of 45 family physicians, 20 general internists, 22 neurologists, and 21 surgeons, located in Kansas, Kentucky, Maryland, Ohio, and Virginia. MEASURES: Work intensity measures included the National Aeronautics and Space Administration-Task Load Index (NASA-TLX), Subjective Work Assessment Technique (SWAT), and Multiple Resource Questionnaire. Stress was measured by the Dundee Stress State Questionnaire. RESULTS: Physicians reported similar magnitude of work intensity on the NASA-TLX and Multiple Resource Questionnaire. On the SWAT, general internists reported work intensity similar to surgeons but significantly lower than family physicians and neurologists (P=0.035). Surgeons reported significantly higher levels of task engagement on the stress measure than the other specialties (P=0.019), significantly higher intensity on physical demand (P < 0.001), and significantly lower intensity on the performance dimensions of the NASA-TLX than the other specialties (P=0.003). Surgeons reported the lowest intensity for temporal demand of all specialties, being significantly lower than either family physicians or neurologists (P=0.014). Family physicians reported the highest intensity on the time dimension of the SWAT, being significantly higher than either general internists or surgeons (P=0.008). CONCLUSIONS: Level of physician work intensity seems to be similar among specialties.