Introduction: This article explores the influence of patient-specific and organisational factors on adherence to program guidelines in an integrated care program targeting older patients. Methods: The integrated care program aimed to offer post-discharge follow-up visits by a municipality nurse and the general practitioner to frail older patients after discharge from hospital. Adherence was measured as step 1) successful referral from the hospital and step 2) completed post-discharge follow-up visit. We followed a cohort of 1,659 patients who were selected to receive a post-discharge follow-up visit in 2014. We obtained unique data from hospitals, municipalities and from administrative registers. Results: We found substantial lack of adherence in both steps of the program: 69% adherence in step 1 and 54% adherence in step 2. In step 1, adherence was related to hospital, and receiving municipal home care prior to admission. In step 2, level of adherence varied according to municipality, the type of general practitioner and the patient’s gender. Conclusion: We found that adherence was strongly related to organisational factors. Adherence differed significantly at all organisational levels (hospital, municipality, general practice), thus indicating challenges in the vertical integration of care. Gender influenced adherence as the only patient-related factor.