The present study aimed at examining the effect of environment on growth and yield performance of some common bean (Phaseolus vulgaris L.) genotypes. The study was conducted during the season of 2007/2008 at SUA Mlali and Mgeta locations in Morogoro region. Ten bean genotypes obtained from SUA Bean Project were used. The beans were SUA90, ROJO, PESA, MSHINDI, ZAWADI, EG10R43, EG21R30, EG10R5, EG10R13 and one local genotype. SUA90, ROJO and one local genotype found in each location were used as a control. A randomized complete block design [RCBD] was used, with three replications at each location. Plot size was 2m x 2m with four rows of 2m, with plant spacing of 20cm x 50cm. Each replication had 10 plots, Net plot having two rows of 2m x 1.5m. Genotypes showed variation on studied variables though there was no significant difference for genotype x environment interaction. The local check performed better for some variables such as yield at the location, Genotypes at Mlali performed better for most of studied variables. From combined analysis, Pesa yielded higher (416kg/ha) while genotypes SUA90 EG10R43, EG21R13 and Zawadi yielded above the average (306 kg/ha) but were unstable and favoured by environment. There was significant positive correlation between yield and days to 50% flowering which implied that later flowering beans results into high yields. Genotype Rojo and EG10R43 were least affected by common bacterial blight at all sites, while genotype EG10R13 was least attacked by angular leaf spot at all locations. For rust, genotypes Zawadi, EG10R5 SUA90 and Pesa were least infected at all locations, these genotypes can be used for crossing programme to have resistant genotype to mentioned diseases. These results on change in relative performance of bean genotypes across studied environments (example seed yield variation) contribute important information about environment effects under Morogoro condition.