Field tests were conducted to evaluate the performance of power tiller drawn and three different sized tractor drawn rotavator at Instructional farm of College of Agric. Engg. and Technology, Anand Agric. University, Godhra, Gujarat. The four range of power source (tractors), i.e. medium sized tractor (35 hp), mini tractor1 (15 hp), mini tractor2 (12 hp) and power tiller (13 hp) and four matching rotavator were selected for seed bed preparation. The soil texture of experimental field was sandy loam and the average moisture content was 15.40 percent at the time of experiment. The experimental plots were laid down side by side in a Randomized block design. The selected four tractor–rotavator combinations were evaluated in the field for seed bed preparation to ensure the most cost effective performance among four. The parameters evaluated were operating speed, draft, wheel slip, fuel consumption, energy and drawbar power requirement, field capacity, field efficiency, soil volume disturbed, soil pulverization and cost of operation. The field efficiency obtained for seed bed preparation with 35 hp medium sized tractor drawn rotavator, 15 hp mini tractor1 drawn rotavator, 12 hp mini tractor2 drawn rotavator and 13 hp power tiller drawn rotavator was 75.11 %, 71.80 %, 70.70% and 64.86 %,respectively. The mean mass diameter obtained after seed bed preparation with 35 hp medium sized tractor drawn rotavator, 15 hp mini tractor1 drawn rotavator, 12 hp mini tractor2 drawn rotavator and 13 hp power tiller drawn rotavator was 11.75 mm,14.71 mm,14.09 mm and 19.10 mm, respectively. The cost of operation per hectare for seed bed preparation with 35 hp medium sized tractor drawn rotavator, 15 hp mini tractor1 drawn rotavator, 12 hp mini tractor2 drawn rotavator and 13 hp power tiller drawn rotavator was rupees 1655.93, 1426.93, 1598.42, 2497.00, respectively. The overall results indicated that 15 hp mini tractor1 drawn rotavator performed better for seed bed preparation with lowest cost of operation per hectare as compared to rest of the three tractor- rotavator combinations under sandy loam soil conditions of the experimental field.