Static postures, repetitive movements and precision demands are causes for musculoskeletal disorders. Features in the design of user interfaces of software contribute to these risks. The user interface can increase risks of musculoskeletal disorders by forcing the user to repeat movements, to maintain static postures, to adopt awkward postures and to perform precise movements and by causing stress. Software design and usage can be improved to reduce these risks. Current guidelines and standards for user interface design however, are mostly focussed on cognitive aspects of human computer interaction and on hardware issues. In addition, current trends towards more browser based software seem to limit attention to these aspects of the user interface. Experiences in consultancy projects and input from experts in the field lead to the conclusion that more attention is needed for this issue. This paper illustrates how the design of the user interface can have an effect on physical risks for musculoskeletal disorders. Also a sample of possible guidelines for software designers will be shown, as well as ways to support users in using software in safe and efficient ways.