Abstract Objectives Despite increasing emphasis on the inclusion of patient input in health technology assessment (HTA) in Europe in particular, questions remain as to the integration of patient insight alongside other HTA inputs. This paper aims to explore how HTA processes, while ensuring the scientific quality of assessments, “make do” with patient knowledge elicited through patients’ involvement mechanisms. Methods The qualitative study analyzed institutional HTA and patient involvement in four European country contexts. We combined documentary analysis with interviews with HTA professionals, patient organizations, and health technology industry representatives, complemented with observational findings made during a research stay at an HTA agency. Results We present three vignettes which showcase how different parameters of assessment become reframed upon the positioning of patient knowledge alongside other forms of evidence and expertise. Each vignette explores patients’ involvement during an assessment of a different type of technology and at a different stage of the HTA process. First, cost-effectiveness considerations were reframed during an appraisal of a rare disease medicine based on patient and clinician input regarding its treatment pathway; in the second vignette reframing amounted to what counts as a meaningful outcome measure for a glucose monitoring device; in the third, evaluating pediatric transplantation services involved reframing an option’s appropriateness from a question of moral to one of legal acceptability. Conclusions Making do with patient knowledge in HTA involves reframing of what is being assessed. Conceptualizing patients’ involvement in this way helps us to consider the inclusion of patient knowledge not as complementary to, but as something that can transform the assessment process.