Performance assessment of irrigation system plays a vital role for the enhancements of the future functioning of the system. Canal sedimentation problems, improper operation and maintenance, irrigation scheduling problems are the main features of woki irrigation scheme. Therefore, the aim of this study was to assess the performance of woki small-scale irrigation scheme using minimum set of performance indicators. The study was also met its objective by the collected and analyzed primary and secondary data of climatic, soil, crop, and flow measurements. The results of internal and external performance indicators showed, conveyance efficiencies of lined and unlined canals were 81.58% and 60.26%; application efficiencies were 50.3%, 43.4%, 48.67%; storage efficiencies were found to be 53.3%, 42.1%, 40.5% at the head, middle and tail reaches respectively; relative water supply and relative irrigation supply were 1.82 and 1.76; irrigation ratio of 0.77 and sustainability of irrigated area 0.86; output per unit irrigation water supplied 0.3 US $/m 3 ; and output per unit water consumed was 0.1 US $/m 3 . Based on these results, it can be concluded that mis-utlization of irrigation water, poor operation and maintenance, and low tillage practices resulted in excessive water wastage and reduced scheme efficiencies. From this, it can be recommended that improvements such as proper irrigation scheduling, setting annual canal maintenance programs, awareness conceptions of users and extension agents about irrigation water utilization, and soil and water management practices should be implemented to upgrade the scheme to its upmost potential. Key words: Performance, performance indicators, irrigation water management