– Maritime pine (Pinus pinaster Ait.) is the first conifer used for reforestation in France and now,covers 2.4 million ha of the Iberian Peninsula. In order to preserve the genetic resources of this economically and ecologically important species prior knowledge,of the distribution of genetic diversity is needed. In this paper, a genetic diversity study was performed using nuclear simple sequence repeats (SSRs or microsatel- lites). Classical parameters of diversity (allelic richness and heterozygosity) and differentiation were estimated for 47 populations of P. pinaster. Most of the populations (40) were collected in France, six populations were also collected in the Iberian Peninsula and one Moroccan population was also included in the study. The population genetic parameters indicated that some populations should be a focus of conservation efforts (hig- her level of diversity, higher allelic richness and presence of rare alleles). A diagnostic test for sample origin was developed to distinguish Corsi- can from Landes populations. Pinus pinaster / nuclear microsatellites / genetic diversity / conservation / provenance identification Résumé – Que nous indiquent les microsatellites nucléaires sur la conservation des ressources génétiques du pin maritime et sur les stra-