An investigation was carried out to ergonomically evaluate the cotton picker by determining the energy expenditure, cardio-vascular load and cardio respiratory stress. Six subjects were selected for the study and they were standardized and calibrated with an electrical ergo meter to compute the V02 max value. Heart rate and oxygen consumption were computed using polar heart rate monitor and oxylog, respectively. Average heartbeat of the 6th and 15th minutes was recorded for the calculation. It was observed that the heart rate of the subjects increased steadily from the beginning of the operation and stabilized in the range of 121.0 ± 4.56 beat/min after 6th minute of operation. The average oxygen consumptions were 0.53 and 0.45 1/min for machine and conventional picking respectively. Average energy expenditure for operation of the cotton picker was 11.16 kJ/min and the operation of the machine could be graded as ‘moderately heavy'. The average percent V02 max (29.71 %) was lesser than that of the acceptable work load (AWL) limits of 35 per cent.