INTRODUCTION Due to the large amount of time that an individual spends indoors on the average@ indoor environmental quality has a significant effect on the health@ comfort@ and productivity of workers (ASHRAE@ 2005). A good thermal environment could help reduce occupants' complaints and absenteeism. Furthermore@ it contributes to occupants' retention and saves money for agencies. Therefore@ it is important to study the relationship between the parameters of thermal environment and productivity. The elusive relationship between thermal environment and productivity has attracted the attention of researchers for many years. Numerous international studies and projects were aimed at demonstrating and documenting the postulated impact of working space quality on occupants' productivity (Srinavin and Mohamed@ 2002). However@ the relationship has been insufficiently explored (Sensharma et al.@ 1998; Mohamed and Srinavin@ 2005; Ye et al.@ 2005). Laboratory and field studies showed that many physical and chemical factors in the working environment might have an impact on the sensation and performance of occupants@ and consequently@ on productivity (Clements et al.@ 1999; Wargocki et al.@ 2000; Ye et al.@ 2005). There is ample evidence that an improved environment could decrease workers' complaints and absenteeism@ thus indirectly enhancing productivity (Sensharma et al.@ 1998). People prefer to stay in a comfortable environment. However@ there is no proof that the maximum level of comfort experiences could lead to maximum productivity (McIntyre@ 1980). In a real working environment@ occupants' comfort and productivity depend on a number of environmental factors. There is no consensus@ however@ on the definition of productivity or on the specific factors in indoor environment that influence productivity. Therefore@ simulated office works were often used in some studies@ such as text-typing from a hard copy onto a computer screen in which spelling@ grammatical@ and logical errors had been inserted (Wargocki et al.@ 1999; Wyon@ 2004; Kosonen and Tan@ 2004). As compared to office work@ factory work is easier to measure@ especially repetitive work. The field surveys conducted in this study were done in two factories in China. One survey was conducted in Zhenjiang City (located in the east of China which is famous for its light industry) from September 2003 to December 2003. The other survey was done in Shanghai from December 2003 to February 2004. In China@ the cool season spans from October to March of the next year. This study focused on the impact of thermal comfort@ indoor air quality@ and some exogenous factors on the occupants' performance or productivity. The research attempted to better understand the relationship among productivity@ workers@ and indoor environment.