Torture can be defined as the deliberate or systematic infliction of physical or mental suffering to force another person to yield information, as a punishment or to destroy a person's identity. The aim of the physiotherapy treatment for persons who have undergone torture is to relieve or reduce pain, correct musculoskeletal dysfunctions, teach the client to cope with pain, and regain body awareness. A good interaction and communication with each refugee is needed to optimize the treatment. The aim of this study was to identify factors important for a good interaction between physiotherapist (PT) and the patient among PTs specialising in refugees who have been tortured. A qualitative multiple case study was done. Ten physiotherapists working within the Red Cross, psychiatry or primary health care, who held positions specialising in treating persons who have undergone torture were interviewed. The interviews were analysed with content analysis. The results showed that the factors important for a good interaction could be summarised into two themes; prerequisites for a good interaction and interaction factors. Five prerequisites for a good interaction with persons who have undergone torture were found: personal characteristics, professional and therapeutic competence and support, language factors, time, and frames. Five factors in the interaction situation were important for a good interaction: cultural factors, treatments tailored to the patient's needs, to develop confidence and trust, religious factors, and capacity to handle negative emotions. All these factors have to be considered to improve the interaction between PTs and persons who have undergone torture.