This paper analyses the regulation of ambulatory care and its impact on physicians careers, using a representative panel of 6;016 French self-employed GPs over the years 1983 to 2004. The beginning of their activity is influenced by the regulated number of places in medical schools, named in France numerus clausus. We show that the policies aimed at manipulating the numerus clausus strongly affect physicians permanent level of earnings. Our empirical approach allows us to identify experience, time and cohort effects in GPs earnings. The estimated cohort effect is very large, revealing that intergenerational inequalities due to fluctuations in the numerus clausus are not negligible. GPs beginning during the eighties have the lowest permanent earnings: they faced the consequences of an unlimited number of places in medical schools in the context of a high density due to the baby-boom numerous cohorts. Conversely, the decrease in the numerus clausus led to an increase in permanent earnings of GPs who began their practice in the mid nineties. Overall, the estimated gap in earnings between "good" and "bad" cohorts may reach 25%. We performed a more thorough analysis of the earnings distribution to examine whether individual unobserved heterogeneity could compensate for average differences between cohorts. Our results about stochastic dominance between earnings distributions by cohort show that it is not the case. [Authors]