Objectives To evaluate the extent and quality of patient involvement reporting in examples of current practice in health research. Design Mixed-methods study. We used a targeted search strategy across three cohorts to identify health research publications that reported patient involvement: original research articles published in 2019 in the British Medical Journal (BMJ), articles listed in the Patient-Centered Outcomes Research Institute (PCORI) database (2019), and articles citing the GRIPP2 (Guidance for Reporting Involvement of Patients and Public) reporting checklist for patient involvement or a critical appraisal guideline for user involvement. Publications were coded according to three coding schemes: € phase of involvement', the GRIPP2-Short Form (GRIPP2-SF) reporting checklist and the critical appraisal guideline. Outcome measures The phase of the study in which patients were actively involved. For the BMJ sample, the proportion of publications that reported patient involvement. The quality of reporting based on the GRIPP2-SF reporting guideline. The quality of patient involvement based on the critical appraisal guideline. Quantitative and qualitative results are reported. Results We included 86 publications that reported patient involvement. Patients were most frequently involved in study design (90% of publications, n=77), followed by study conduct (71%, n=61) and dissemination (42%, n=36). Reporting of patient involvement was often incomplete, for example, only 40% of publications (n=34) reported the aim of patient involvement. While the methods (57%, n=49) and results (59%, n=51) of involvement were reported more frequently, reporting was often unspecific and the influence of patients' input remained vague. Therefore, a systematic assessment of the quality and impact of patient involvement according to the critical appraisal guideline was not feasible across samples. Conclusions As patient involvement is increasingly seen as an integral part of the research process and requested by funding bodies, it is essential that researchers receive specific guidance on how to report patient involvement activities. Complete reporting builds the foundation for assessing the quality of patient involvement and its impact on research.