Several studies indicate a relationship between ergonomic work conditions and the quality of the work. The purpose of this study was to evaluate relationships between a number of ergonomic conditions and product quality in car assembly. The most physically demanding tasks, the tasks with the most difficult parts to assemble, and the most psychologically demanding tasks, were identified by interviews with experienced assembly workers. Information on quality deficiencies was obtained from the internal quality statistics of the company and from interviews with quality control personnel. The results showed that the quality deficiencies were three times as common for the work tasks with ergonomics problems, compared with the other tasks. An increased risk of quality deficiencies was seen for all three categories of ergonomics problems investigated. Direct causes of quality deficiencies were identified, such as discomfort from strained parts of the body, organizational factors and time pressure. The analyses pointed to certain types of task that were more likely than others to cause quality problems. The results also showed that an important factor for job satisfaction was the possibility for the workers to perform their tasks with high quality. The study therefore confirms close relationships between ergonomics and quality, and thereby points to the possibility of conducting integrated change programmes aimed at improving work quality and work conditions simultaneously.