In computer workers psychological factors and physical fitness may play an important role in the onset and course of non-specific work-related upper limb disorders (WRULD) beyond socio-demographic factors. Based on our experiences in daily practice we assumed that pain catastrophizing and other psychological variables such as perfectionism, anxiety state and trait, and low physical fitness, are possibly associated with the occurrence of WRULD. We aim to study the association between pain catastrophizing, perfectionism, anxiety (state and trait), physical fitness, sex and level of education and the occurrence of WRULD, controlling for age as a confounder. Eighty-eight computer workers with early non-specific WRULD, who had been recruited for an intervention study, were compared with 31 healthy computer workers (controls) recruited from different departments of a university. This cross-sectional case-control study examined the influence of aforementioned variables on WRULD by means of logistic regression analyses. Among the different predictor variables investigated, pain catastrophizing (OR=1.37; 95%CI 1.17-1.59) and lower physical fitness had a positive relationship with WRULD (OR=0.65; 95%CI 0.48-0.87). According to this study, pain catastrophizing and lower physical fitness seem to be associated with early non-specific WRULD in computer workers. Prospective studies are needed to unravel these relationships.