An experiment was conducted with drought-tolerant and susceptible genotypes to find out the key traits that determine drought tolerance in cassava. The drought-tolerant clone 8S501 and the two susceptible clones H-97 and CR43-11 were planted in the field in a Randomized Block Design and the drought stress was imposed when the plants were three months old. The observations were measured at the beginning of the stress period (0-stress), 30 and 75 days of stress. The repeated measures ANOVA stated that there were significant differences among the genotypes, stress duration and their interaction for the majority of the traits. Growth, development and tuber yield of cassava was not significantly affected up to 30 days of drought stress. There was a greater decline in LA, TBM, CGR, RGR and NAR between 30 and 75 days of drought stress suggesting that measures are to be taken if drought stress prolongs for more than 30 days to realize optimum growth and yield of cassava. There was no increment in TY and PSR after 30 days of stress. A greater reduction was observed from 30 to 75 days of stress in leaf TC and CP content. There was a considerable increase in proline and total phenols content in the leaf from 30 to 75 days of stress. The inherent free radical scavenging activity measured as DPPH, FRAP and ABTS assays also demonstrated a notable increase in antioxidant activity at 75 days of drought stress. The early vigour in terms of initial high leafiness, leaf area, tuber yield, proportion of storage roots and total biomass in the first three months after planting facilitated the clone 8S501 to effectively tolerate the drought stress conditions.