Abstract: Background and Objective: Cassava planting usually takes place in the latter part of the rainy season, which thereby exposes the cassava to the prolonged drought of the upcoming dry season. The objective of this research was to investigate the effects of irrigation regimes on growth, yield and starch content of cassava. Materials and Methods: Two cassava varieties were planted in split-plot design, late in the rainy season of 2014/2015. Cassava varieties (Huaybong 80 and Rayong 11) were assigned as the main-plot. Sub-plots were cultivated with 5 different water regimes: (1) The crop received 15 mm of water when the daily cumulative pan evaporation value reached 40 mm [I-15, EV-40 mm] and, correspondingly, (2) [I-15, EV-60 mm], (3) [I-30, EV-40 mm], (4) [I-30, EV-60 mm] and (5) The no-irrigation (control) group [I-0]. All treatments received similar amounts of natural rainfall during the rainy season. One way-analysis of variance (ANOVA) was performed according to a split plot design using statistics version 8 (STAT 8) software. Means were separated by Least Significant Difference (LSD) at 0.05 probability level. Results: Irrigation treatments in each of the irrigated sub plots significantly increased the storage root yields over the non-irrigated control across the two varieties (p<0.01). Total water usage (in descending order) of 1363, 1153, 1108, 1003 and 853 mm were recorded for sub-plots (3) [I-30, EV-40 mm], (4) [I-30, EV-60 mm], (1) [I-15, EV-40 mm], (2) [I-15, EV-60 mm] and (5) [I-0], respectively. The water use efficiency determined within cropping season ranged from 62.8-74.7 kg ha–1 mm–1. Percentages of total water applied from total water used in sub-plots (3) [I-30, EV-40 mm], (4) [I-30, EV-60 mm], (1) [I-15, EV-40 mm] and (2) [I-15, EV-60 mm] were 37.4, 26.0, 23.0 and 14.9%, respectively. Conclusion: The water regime of [I-30, EV-40 mm] (sub-plot 3) produced the highest fresh (85.6 t ha–1) and dry (37.5 t ha–1) storage root yields across both varieties; however, the Huaybong 80 variety produced significantly higher storage root yields than those of the Rayong 11 variety across all irrigation regimes (p<0.05). Neither the irrigation regime nor the variety of cassava had any significant effect on the starch content of the storage root.