Because of specific features of his practice (comprehensive access to different social classes, provision of care for the whole set of diseases, length of follow up) general practitioner is in a privileged position to give evidence and can act against social inequalities in health. Understand and measure the effects of social characteristics on patients health is the first action to be done because the clinical description and the natural history of these inequalities are in fact very roughly known. The general practitioner can further act by learning how to concentrate his work to increase quality of care among male patients in workers and clerical or service staff categories, ensuring that needs are met as far as possible. Initiation of this work is the task of teaching practitioners and health care networks and provide a subject for primary care research. As a general rule, differences between social groups for the frequency or the prognosis of a given disease will be associated with, all together, accumulation of 'classical' risk factors for the considered disease, inequalities in care uptake partially due to a socially patterned access to the specialists, and an element of residual vulnerability, non explained by the previous two, which is the matter for an active research at the present time.