Background: Psychosocial problems in cancer patients are often unrecognized and untreated due to the low awareness of the existence of these problems or pressures of time. The awareness of the need to identify psychosocial problems in cancer patients is growing and has affected the development of screening instruments. This study explored the usefulness and feasibility of using a screening instrument (SIPP: Screening Inventory of Psychosocial Problems) to identify psychosocial problems in cancer patients receiving curative radiotherapy treatment (RT). Methods: The study was conducted in a radiation oncology department in the Netherlands. Several methods were used to document the usefulness and feasibility of the SIPP. Data were collected using self-report questionnaires completed by seven radiotherapists and 268 cancer patients. Results: Regarding the screening procedure 33 patients were offered to consult a psychosocial care provider (e.g. social worker, psychologist) during the first consultation with their radiotherapist. Of these patients, 31 patients suffered from at least sub-clinical symptoms and two patients hardly suffered from any symptoms. Patients' acceptance rate 63.6% (21/33) was high. Patients were positive about the content of the SIPP (mean scores vary from 8.00 to 8.88, out of a range between 0 and 10) and about the importance of discussing items of the SIPP with their radiotherapist (mean score = 7.42). Radiotherapists' perspectives about the contribution of the SIPP to discuss the different psychosocial problems were mixed (mean scores varied from 3.17 to 4.67). Patients were more positive about discussing items of the SIPP if the radiotherapists had positive attitudes towards screening and discussing psychosocial problems. Conclusions: The screening procedure appeared to be feasible in a radiotherapy department. In general, patients' perspectives were at least moderate. Radiotherapists considered the usefulness and feasibility of the SIPP generally to be lower, but their evaluations were mixed. A positive attitude to using screening instruments like the SIPP needs to be encouraged among radiotherapists, as this may not only improve the usefulness of a screening instrument, but also patients' satisfaction with care.