Abstract Not all patients on dialysis want to be registered on the kidney transplantation (KT) waiting list and undergo transplantation. The aim of this convergent mixed methods study was to determine the features of patients refusing to be registered on the KT waiting list and the reasons. Quantitative data on all 2017–2019 incident 18–85-year-old dialysis patients, eligible for KT, were extracted from the REIN registry in France. Qualitative data were collected through semi-structured interviews with patients on dialysis and nephrologists from the Bretagne, Île-de-France and Normandie French regions. The binary logistic regression method was used to identify factors/reasons associated with registration refusal and an inductive thematic analysis was performed on qualitative data. The quantitative analysis included data of 10,512 patients (mean age = 57.5 years). Among them, 860 (8.18%) refused to be registered on the KT waiting list. The multivariate analysis showed that women were 83% more likely to refuse registration compared with men. The qualitative analysis included 21 patients and 11 nephrologists. The integration of the results from the quantitative and qualitative analyses allowed identifying some factors associated with the registration refusal. Most of these factors converged across analyses. These included age, sex/gender, autonomy on dialysis and comorbidities. The integration of the results highlighted some divergence concerning sex/gender and autonomy and an area of expansion related to comorbidities. In conclusion, the patient age, sex/gender and comorbidities appear to play an important role in the refusal to be registered on the waiting list. Interventions focused on these factors might help to improve KT accessibility in France.