The aim of this research was to assess for levels of drought tolerance among common bean (Phaseolus vulgaris L.) lines developed for drought tolerance; grown under non-stress (NS) and drought-stress (DS) water conditions. The research was conducted at Sokoine University of Agriculture (SUA) located at 6 0 5’ latitude south, 37 0 3’ longitude east and 525 m.a.s.l. It was done in a screen house. The experimental design was Completely Randomized Design (CRD), two water regimes and twelve bean lines were combined in split- plot arrangement. Water regimes were the main plots and bean lines were sub-plots. The soil in pots was irrigated to 95 ± 5% field capacity (fc) which was determined by a tensiometers reading. Three seeds were planted in each pot, after germination (7-10 days) thinning was done to leave two (2) uniform bean plants in each pot. Then the NS and DS treatments were initiated at two weeks after germination. For non-stress (NS) treatment, irrigation was done once/day depending on the requirements of the plant and environmental conditions receiving water to make 95 ± 5% field capacity, which kept the plant water-stress free. In drought stress, watering was cut down to mimick a drought condition. Stress was imposed starting at different stages i.e. before flowering, at podding and thereafter stress condition was maintained at 20 ± 5 % fc. Data were collected for plant height, pod length, leaf area, number of seeds per pod, number of pods per plant and seed weight per plant. The results showed that some lines had a high capacity for tolerating DS conditions namely RWR 109, UBR (92) 09, MMS 243, CNF 5547, HHL MD 30-75 and G 4523.