Background: Tolvaptan can slow down renal function decline in autosomal dominant polycystic kidney disease (-ADPKD). While there is consensus across international recommendations that the drug should only be used in patients with high risk of rapid progression, identification criteria for rapid progression vary. Here, we investigated different assessment strategies using a real-life ADPKD cohort. Methods: Observational retrospective cohort analysis. The study included 131 ADPKD patients aged 19–78 years who were referred to the Hannover Medical School outpatient clinic for evaluation of tolvaptan treatment. Six different assessment strategies for tolvaptan eligibility were tested for each patient. Comparative analysis for different assessments was performed in the total study population, the subpopulation with available computed tomography/magnetic resonance imaging data, and the genotyped subpopulation. Results: Comparing 6 assessment strategies revealed strong variations in the individual selection processes resulting in treatment recommendations for 14.5–64.9% of patients. The highest patient number was selected by the Scottish and the lowest by the Japanese approach. Few patients had positive recommendations by all 6 systems, but strong congruency was observed between the Scottish, U.K. and Canadian patient selection. The lowest number of overlapping patients was found between the Japanese and the ERA-EDTA selection. Important discrepancies were also found between the ERA-EDTA and the U.S. system due to different emphases on parameters of kidney function versus kidney volume. Limitations of the study included the restricted sample size, heterogeneity in parameter availability and lack of outcome data. Conclusions: The study draws attention to important discrepancies between different decision algorithms for tolvaptan eligibility in ADPKD patients.