Heat stress is considered to be the sum of heat generated in the body (metabolic heat) plus the heat gained from the environment (environmental heat) minus the heat lost from the body to the environment. The consequences of heat stress can caused heat disorder such as heat stroke, heat syncope, heat exhaustion, heat cramps and other heat related diseases. The objective of this study was to compare the pattern of heat stress in each section. A crosssectional study was carried out in two sections (Paintshop A and Bodyshop B) in a selected automotive assembly plant in Selangor to monitor the environmental heat stress. The environmental heat monitoring was done on 89 March 2005. Heat stress monitor (Model: QUESTemp o 34 Thermal Environment Monitor, Quest Technologies, USA) was used to record the pattern of heat exposure in the workplace over a period of eight hours. Heat parameters such as dry temperature, wet temperature, globe temperature and relative humidity were measured. Wet Bulb Globe Temperature index (WBGT) and workload evaluation were used to compare both sections. Heat parameters such as timeweighted average wet bulb globe temperature for indoor setting (TWAWBGT indoor ), dry temperature (DB), natural wet bulb temperature (WB), globe temperature (GB) in Paintshop A were higher than those in Bodyshop B. The relative humidity in Paintshop A was hotdry compared to Bodyshop B which is hotwarm. Paintshop A was considered a hot area compared to Bodyshop B which is normal. Workers in both sections were not faced with heat stress problems because they were worked under acceptable condition according to American Conference of Governmental Industrial Hygienists standard. Both sections in the automotive assembly plant exhibited acceptable working condition for workers in a tropical environment.