ObjectivesTo evaluate the extent and quality of patient involvement reporting in examples of current practice in health research. DesignMixed-methods study. We used a targeted search strategy across three cohorts to identify health research publications that reported patient involvement: publications published in The BMJ, publications listed in the PCORI database, and publications citing the GRIPP2 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-SF reporting checklist, and the critical appraisal guideline. Outcome measuresThe 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 short form reporting guideline. The quality of patient involvement based on the critical appraisal guideline. Quantitative and qualitative results are reported. ResultsWe included 87 publications that reported patient involvement. Patients were most frequently involved in study design (90% of publications, n=78), followed by study conduct (70%, n=61), and dissemination (40%, n=35). Reporting of patient involvement was often incomplete, e.g., only 39% of publications (n=34) reported the aim of patient involvement. While the methods (56%, n=49) and results (59%, n=51) of involvement were reported more frequently, qualitative analyses showed that 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. ConclusionsAs 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. PROTOCOLThe protocol was published on the Open Science Framework: https://osf.io/vntgu/ STRENGTHS AND LIMITATIONSO_LIA targeted search strategy was used to identify examples of patient involvement reporting in a variety of publication types and study designs in health research C_LIO_LIA mixed-methods approach allowed for an analysis of both the completeness and quality of patient involvement reporting C_LIO_LIIn this study, we coded statements reporting on patient involvement in 87 health research publications that may be adapted for further use C_LIO_LIReporting of patient involvement was insufficiently detailed to allow for a systematic assessment of the quality of patient involvement C_LI