Trust in physicians is the patient's optimistic acceptance of vulnerability and the expectation that the physician will do what is best for his/her welfare. This study was undertaken to develop a conceptual understanding of the dimensions and determinants of trust in physicians in healthcare settings in resource-poor, developing countries. A cross-sectional household survey was conducted on a sample of 625 men and women from urban and rural areas in Tamil Nadu, India. The sample was selected using a multistage sampling method and a pre-tested structured questionnaire was utilised. The questionnaire covered the five dimensions of trust: perceived competence of the physician, assurance of treatment, confidence in the physician, loyalty towards him/her, and respect for him/her. Items covering four main factors that influence trust, ie shared identity, the physician's behaviour, personal involvement of the physician and level of comfort with him/her, were included in the questionnaire. A structural equation model was constructed with the dimensions of trust on one hand and the four factors influencing trust on the other. Trust in physicians is based more on notional constructs, such as assurance of treatment (b=0.714, p<0.001) and respect for the physician (b=0.763, p<0.001),than objective assessments, such as the physician's competence (b=0.607, p<0.001). Feeling comfortable with the physician (b=0.630, p<0.001) and the physician's communication skills (b=0.253, p<0.001) significantly influence the level of trust. The former is correlated with the personal involvement of the physician (r=0.124, p<0.001), and so is the latter (r=0.152, p<0.001). The overall model has a good statistical fit. The factors that give rise to trust in physicians vary with the sociocultural context.