This paper elucidates the effect of environmental stressors, viz. noise and illumination, on operator’s performance. The effect of environmental stressor on the performance of tasks is studied in a workshop where work situations are simulated. The study was conducted on two machines, namely a lathe and a shaper, to explore the individual as well as combined effect of noise and illumination levels on operator’s performance. The performance was found to decrease slowly as either the illumination level or noise level increased while keeping the other one fixed. But the performance level decreased more rapidly as both the noise and illumination level were increased simultaneously. The relationship between the equivalent noise level or illumination level and workers performance was found to be statistically significant as the correlation coefficients of all the relations were high. © 2007 Institute of Noise Control Engineering.