A population of seven general surgeons in a prepaid group practice previously shown to have a mean operative work load of 9.2 HE per week were found to have a mean standardized seven day working week of 56.2 hours exclusive of evening activities. The surgeons also devoted a mean of 6.7 evening hours to professional activities for a total working week of 62.9 hours. Comparisons of the time utilization of this population of general surgeons with a population of previously studied community surgeons revealed that the prepaid group surgeons were able to maintain a surgical output more than double that of the community surgeons without having to devote twice as much time to professional activities. Economies in the utilization of surgical manpower in the prepaid group appear to stem from geographic and specialty restrictions on the scope of work of the surgeons, from a reduction of waiting time in the office, and from the utilization of paraprofessional personnel for operative assisting.