The focus of the study is the analysis of changes in health-related quality of life in various cancer entities during and after an inpatient rehabilitation programme. In a multicentre longitudinal study, a total of 211 cancer patients (breast cancer: N = 84; prostate cancer: N = 90; colon cancer: N = 37) were asked about their quality of life (EORTC QLQ-C30; HADS) at the beginning, the end and 3 months after the end of the rehabilitation programme. In different domains of quality of life significant and mostly clinically relevant improvements were found during rehabilitation. The breast and prostate cancer patients improved most in emotional functioning, colon cancer patients in global quality of life. With regard to the severity of symptoms, the fatigue burden improved in breast and colon cancer patients, nausea in the prostate cancer patients. However, they are increases 3 months after rehabilitation. Functional burdens improved 3 months after the end of rehabilitation in the physical domain for all cancer patients. For breast cancer patients, emotional functioning decreased significantly 3 months after rehabilitation. An inpatient oncological rehabilitation programme can lead to an improvement in quality of life.