This systematic review examines patient engagement in healthcare research, aiming to answer four key questions: how to identify patient representatives, how to engage them in research design and conduct, what benefits patient engagement provides, and what harms or barriers exist. The review included 142 studies, showing that patient engagement is generally feasible but comes with costs and risks of being tokenistic. Engagement was most common in the early stages of research (agenda setting and protocol development) and less so during execution and translation. Studies found that patient engagement increased study enrollment and helped researchers secure funding, design protocols, and choose relevant outcomes. Common challenges included logistical issues and concerns about tokenistic engagement. While no comparative studies provided evidence for best practices, many methods were described in the literature. Patient engagement in all research phases seems feasible, especially in populations traditionally considered difficult to reach. However, potential harms and costs must be balanced against the benefits. Future research is needed to better understand the value of patient engagement and how to implement it effectively. The review highlights the importance of patient involvement in research, which can improve the credibility and applicability of findings. The study was conducted with input from patients, researchers, and experts, and used a comprehensive search strategy to ensure thorough coverage of the literature. The findings suggest that while patient engagement is feasible, it requires careful consideration to avoid tokenism and ensure meaningful participation.This systematic review examines patient engagement in healthcare research, aiming to answer four key questions: how to identify patient representatives, how to engage them in research design and conduct, what benefits patient engagement provides, and what harms or barriers exist. The review included 142 studies, showing that patient engagement is generally feasible but comes with costs and risks of being tokenistic. Engagement was most common in the early stages of research (agenda setting and protocol development) and less so during execution and translation. Studies found that patient engagement increased study enrollment and helped researchers secure funding, design protocols, and choose relevant outcomes. Common challenges included logistical issues and concerns about tokenistic engagement. While no comparative studies provided evidence for best practices, many methods were described in the literature. Patient engagement in all research phases seems feasible, especially in populations traditionally considered difficult to reach. However, potential harms and costs must be balanced against the benefits. Future research is needed to better understand the value of patient engagement and how to implement it effectively. The review highlights the importance of patient involvement in research, which can improve the credibility and applicability of findings. The study was conducted with input from patients, researchers, and experts, and used a comprehensive search strategy to ensure thorough coverage of the literature. The findings suggest that while patient engagement is feasible, it requires careful consideration to avoid tokenism and ensure meaningful participation.