Genetic erosion is observed in traditional populations of onion in West Africa. The present study aimed to assess the agronomical potential for six important traits of 14 landraces collected in West Africa. A multivariate procedure was used to establish a classification within this germplasm on the basis of these traits. The phenotypic variability both within and between landraces is considerable but could be due to traditional agricultural practices still occurring in this area. Three statistically coherent clusters have been identified despite the great phenotypic variation between landraces and could be a basis for building a core collection of West African onion germplasm. This first analysis of traditional onion landraces provides convincing information regarding their agronomic potential. Key words : Allium cepa L., onion, genetic resources, diversity.