In this thesis the situation concerning women's musculoskeletal disorders in three different types of workplaces is studied, and differences in women's and men's working conditions which affect this situation are identified. How diffe-rences in working conditions are constructed and reconstructed in and by gen-dered processes is analysed, and this analysis also shows how the work organiza-tions are gendered and gendering. The empirical material consists of studies of one electronics plant, two grocery stores, and five mail delivering offices. A qua-litative method is used. The study shows how horizontal and vertical sex segregation at the electronics plant and in the grocery stores resulted in women continually performing mo-notonous tasks, thus being exposed to high risks of developing musculoskeletal disorders. At the mail delivery offices where women and men performed the same work tasks the working conditions nevertheless were different. Recent changes of the organization of work had led to sex-specific consequences, such as the workload becoming heavier especially for women. The psychosocial work environments also varied. At the studied workplaces construction of gender and construction of diffe-rences in working conditions were intertwined in processes that also led to the reconstruction of men's dominance and women's subordination. Gendered processes were results of management policies, affected by the strategies of the local unions, and tied to the extended social relations. Gendered processes were also present in, and re-created by, the day-by-day interaction between fellow workers. Both women and men at the workplaces were faced with expectations of appropriate gender behaviour, and both women and men often, but not al-ways, conformed to these expectations. In the thesis an analysis of sexuality and heteronormativity at the studied workplaces is integrated in the analysis of the construction of gender and diffe-rent working conditions, in order to reach an increased understanding of gende-red processes in the work organizations.