The objectives of this questionnaire study of all primary care physicians (N = 154) who had ever worked in eight New England prepaid group practices (PGPs) include 1) calculation of turnover rates, 2) comparison of those who stayed in (stayers) versus those who left (leavers) the PGPs, and 3) description of reasons given for leaving. An annual turnover rate of 3.9 to 6.3 per cent, depending upon the measure, was within the range reported by others. Factors associated with stayer-leaver status were experiences before and during the physician's PGP tenure. Leavers reported pre-PGP experience in fee-for-service, hospital-based, and academic positions, and while in the PGPs, they reported constraints on autonomy, independence, and professional development. Leavers reported higher incomes and longer working hours in their new practices. They cited the potential for greater autonomy as the reason for leaving. The findings and study limitations are discussed.