The effect of two plant densities and genotype in growth and N -accumulation of common vetch, used as green manure was investigated. The experiment field was settled in central Greece. The study soil was clayey, classified as Vertisol. The results demonstrated a significant effect (P < 0.05) of plant density in all growth indicates. Significant differences (P < 0.05) were detected in growth indices, biomass productivity and N uptake, among different genotypes of common vetch regardless plant density. Contrary, no effect of plant density was observed in N concentration of plant tissue in all varieties and mixtures. In particular, LAI increased with high rates from crop emergence, reaching values above 3.5 m 2 m -2 in all cases, and maintained high values for more than two months. Also biomass production was significant lower in genotypes and mixtures when cultivated with plant density of 100 Kg ha -1 than with plant density of 180 Kg ha -1.