BACKGROUND: Case management (CM) models based on experienced nurses are increasingly used to improve coordination and continuity of care for patients with complex health care needs. Anyway, little is known about the effects of hospital-based CM in cancer care.Aim.To analyse the effects of hospital-based CM on (i) GPs' evaluation of information from the hospital and collaboration with the hospital staff and (ii) patients' contacts with GPs during daytime and out of hours. DESIGN: A randomized controlled trial allocated 280 colorectal cancer patients 1:1 to either a control group or CM intervention. SETTING: Patients were recruited at a Danish surgical department. METHODS: An ad hoc piloted questionnaire was sent to all patients' GPs 30 weeks after patients' recruitment and the responses from the two groups of GPs were compared. Registry data on patients' contacts with general practice during daytime and out of hours were collected 9 months after recruitment and the data from the two groups were compared quarterly. RESULTS: CM was associated with an overall tendency towards more positive GP evaluations, which for 3 of 20 items reached statistical significance. Statistically significantly fewer GPs of CM patients reported contacting the hospital. CM did not affect the number of patient contacts with the GPs during the daytime, but CM patients showed a tendency towards more contacts to the out-of-hours GP services than non-CM patients. CONCLUSIONS: CM was appreciated by the GPs and reduced their need for subsequent hospital contact. CM increased the number of patient contacts to the out-of-hours GP services.