Field experiments were conducted in Al-Muthanna Province, Iraq in order to evaluate the Body parts discomfort score and physiological cost of tractor operator during tillage operation while using mould board plough. Three subjects represented 50th percentile of their population were chosen for this study. We used the Corlett and Bishop Technique to evaluate the degree of discomfort in various body parts. According to the findings, both BPDS and HR went up as the engine rpm went up. The most common sites of pain were the neck, lower back, both legs, both feet, and both wrists. The minimum mean of BPDS was 18.90 at tillage depth 10 cm and engine speed 1000 rpm. While the maximum of BPDS was 28.67 at tillage depth 30 cm and 2000 rpm tractor engine speed. The variation in BPDS due to tillage depth and tractor engine speed was significant at 5 per cent level. The lowest value of HR of the operator was obtained at 10 cm depth and 1000rpm whereas the highest value was obtained at 30 cm and 2000 rpm tractor engine speed. The values were 88 and 101 beats/min respectively. Tillage operation with a mould board plough was associated with a "low" workload in steady state, as seen by the observed HR values for all participants, with the exception of 30 cm depth at 2000 engine speed, where the effort was moderate. The variation in ΔHR due to tillage depth and tractor engine speed was significant at 5 per cent level.