- Background. There is little empirical research examining the effects of burnout on objective measures of primary care physicians’ behaviour in the medical encounter. Objectives. We studied possible associations between primary care physicians’ burnout and the rates of referrals. We conceptualized referral rate as a negative outcome of burnout because high and unnecessary referral rates incur extra costs to health care systems. Methods. In this cross-sectional study, 136 primary care physicians in one district of one Israeli health maintenance organization (HMO) completed the Maslach Burnout Inventory in the presence of an interviewer. Data on each physician’s objective workload and number of referrals for high- and low-cost imaging tests, specialist clinics and treatments by nurses were collected from the HMO’s databases. Results. Due to high correlations between referral rate indicators, a Confirmatory Factor Analysis revealed one factor: ‘referrals for diagnostic tests and specialist clinics’. Path Analysis using Structural Equation Modelling explained a total of 18.1% of referral rate variance, with boardcertified specialist mostly associated ( β = 0.31, P < 0.01), followed by burnout (β = 0.20, P < 0.05) and objective workload (β = 0.18, P < 0.05). Conclusions. In this preliminary investigation, we found that referral rates for diagnostic tests and specialist clinics increased independently for board-certified specialists (compared with GPs), for those with higher burnout levels and when objective workload increases. These findings support the conceptualization of referrals rates as objectively measured negative outcomes of burnout. Further replications with other objective outcomes, additional HMOs and bigger samples are warranted.