Patient involvement is an increasingly recognized cornerstone of effective Health Technology Assessment (HTA). Clear, accessible information empowers patient organizations to contribute meaningfully to HTA. Therefore, an international Summary Information for Patient Groups template was developed to provide plain language summaries of new medicines being assessed. Pilots using the template were conducted in Australia in 2021 and England in 2022, providing a trial within the HTA process. In Australia, the Consumer Evidence and Engagement Unit (CEEU) used a workshop and survey, together with key stakeholder interviews, to gather feedback. In England, the National Institute for Health and Care Excellence used public consultation, surveys, and a Short-Life Working Group (SLWG). An advisory board with patient organizations provided additional insights. The feedback enabled members of the HTA International Patient and Citizen Involvement in HTA Interest Group to evaluate the potential to enhance patient organization submissions to HTA bodies and to provide recommendations on the template’s implementation in HTA processes. The pilots highlighted that plain language summaries increased confidence and reduced preparation time for patient organization input to HTA. Other nonexpert stakeholders also found them valuable for fostering understanding. However, challenges remain, including mitigating bias in completed templates, allocating sufficient resources, and integrating into existing processes. The evaluation concludes that the approach holds significant potential to enhance patient organization involvement in HTA. Recommendations include setting up multi-stakeholder SLWGs, ensuring early access to summaries, and aligning implementation with local regulations. These insights provide guidance for HTA bodies to develop an approach to support patient involvement.