OBJECTIVE: Evidence on re-appraisals of health technologies in Germany is limited, and for rare disease treatments (RDTs) the Federal Joint Committee follows different processes (limited or regular) depending on whether an annual revenue threshold has been exceeded. Our objective is to better understand (re)-appraisal processes and their outcomes for RDTs in Germany. METHODS: We analysed appraisal documents of 55 RDT indications for which an initial appraisal and a re-appraisal were conducted between 2011 and 2023. We extracted information for the type of evidence, the risk of bias, the availability of additional evidence, and the change in the maturity of survival data as proxies for evidence quality. Specifically, we reviewed the reasons for conducting re-appraisals; examined how evidence quality and the clinical benefit rating (CBR) differed between initial appraisals and re-appraisals; and explored the association between evidence quality and (i) the CBR and (ii) the change in the CBR following re-appraisal. RESULTS: Most re-appraisals were conducted because the annual revenue threshold was exceeded, or the initial appraisal resolution was time-limited. Almost all initial appraisals used the limited process, while the majority of re-appraisals used the regular process. The CBR increased in only nine and decreased in 21 of 55 re-appraisals. There was some evidence that re-appraisals with an accepted randomised controlled trial were significantly more likely to achieve a higher CBR. CONCLUSIONS: Findings confirmed that reasons and processes for conducting re-appraisals of RDTs in Germany differ. Further, high CBRs in re-appraisals were not common and evidence quality in initial appraisals and re-appraisals was limited.