In Ethiopia irrigation subsector is chosen as the policy option in stimulating sustainable economic growth in rural areas. Irrigation development in the country is confronted by many problems and it performs below its potential. Therefore in this study irrigation scheme performance assessment is vital to identify performance gaps and to improve scheme performances. However, the performance of Branti small scale irrigation scheme in South Achefer Woreda Ahuri Keltafa Kebele was not assessed up to now. Primary and secondary data were collected in the study. Secondary data from different reports and primary data through field measurements, key informant interviews and group discussions were collected. For performance evaluation of the irrigation scheme three farmers’ fields were selected from head, middle and tail water users. As a result application efficiency (Ea), conveyance efficiency (Ec), water storage efficiency (Es), deep percolation fraction (DPF) and overall scheme efficiency were determined and their average values were found to be 17.05%, 84.74%, 50.44%, 82.95%, and 14.58%, respectively. Evaluation of irrigation water requirement and crop water requirement of main crops were evaluated using CROPWAT 8. The irrigation water requirement of onion, pepper and potato grown in the study area are 389.8, 372.4 and 388.9mm/season respectively. Water delivery performance of the irrigation scheme was 43.74% which result in 56.26 % of reduction of the capacity of the intake canal. Finally structured questionnaires and group discussions were used to assess the attitude of farmers’ about the performance of their irrigation scheme. The respondents’ response revealed that the major causes for underperformance of the scheme are seepage from the headwork and/or canals, sedimentation and structural failure. Therefore, the conveyance system should be improved through regular canal cleaning and maintenance of canal structures and constructing flow control gates (canal gates). In general performance of the irrigation scheme was rated as poor and crop pattern of the study area was organized in CROPWAT 8.0 model along with necessary data such as climate, soil and crop data.