AimsThe aim of this study is to evaluate how critical patient involvement is in pharmacist‐led clinical medication reviews and in identifying the most significant clinical drug‐related problems (DRPs).MethodsPharmacist‐led clinical medication reviews were conducted with 161 consenting patients aged ≥75 years with at least seven prescribed medicines, living independently at home in Finland. A pharmacist, a nurse and a physician evaluated the clinical significance of the DRPs identified during the patient interview at an interprofessional case conference. It was evaluated whether the most significant clinical DRPs could also have been identified through reviewing the medication list only or the medication list and certain patient details.ResultsAltogether, the 111 most significant clinical DRPs were evaluated. Only 6% could have been identified through reviewing the medication list only, and 16% through reviewing the medication list and certain patient details. Hence, 84% of the most significant clinical DRPs could only have been identified with patient involvement. The most common DRPs were: poor therapy control (25%); nonoptimal drug (22%); intentional nonadherence (12%); and additional drug needed (11%). patient involvement was critical when identifying DRPs related to additional drug needed, unintentional nonadherence, use of over‐the‐counter medicines or dietary supplements, or contradictions in counselling.ConclusionPatient involvement is essential when identifying clinical DRPs. Indeed, poor therapy control, nonoptimal drug use, intentional or unintentional nonadherence might otherwise be missed.