The walking behind harvester (TNS Model 4S-120 imported) was evaluated for its performance by harvesting of wheat crops. The field evaluation was carried out at Kulumsa Agricultural Research Center experimental site. Parameters and measurements considered during this study were crop parameters, operating parameters of the harvesting machine, harvesting losses and cost of harvesting. The average effective field capacity and field efficiency of the harvester was found to be 0.182 ha/h and 81% respectively whereas the effective field capacity in manual harvesting was 0.008 ha/h. Fuel consumption of the reaper was 0.92 lit/h, 5.08 lit/ha. Average value of harvest losses in mechanical harvesting was 1.42 percent only whereas average value of harvesting losses in manual harvesting was 1.73% which is more than that of mechanical harvesting. The cost of harvesting for harvester and for manual harvesting were 479Birr/ha and 1600Birr/ha respectively. The percent saving in the cost of harvesting is reduced by 30% harvesting of wheat with harvester over manual harvesting. Hence, the machine harvesting would be feasible and economical compared to manual harvesting method in terms of time, money and labor requirement. Keywords: walking behind harvester, field capacity, field efficiency, harvesting lose. DOI: 10.7176/ISDE/12-2-01 Publication date: April 30 th 2021