BACKGROUND: In order to ensure eligibility for living kidney donation, donor candidates undergo a thorough medical evaluation. This process might reveal hitherto undetected medical conditions, leading to refusal of the kidney donor candidate. Detection of such conditions may, however, also have a lifesaving effect. We report on 13 years of data from our living donor transplantation program on kidney donor candidates who were diagnosed with major medical conditions during evaluation. MATERIALS AND METHODS: We performed a retrospective analysis of living kidney donor candidates who attended our transplant center between 01/2007 and 12/2019. The main focus was on newly diagnosed medical conditions that required immediate medical attention and their prognostic significance. RESULTS: Of the 436 donor candidates who were evaluated for living kidney donation at our transplant center, 192 (44%) were accepted, while 244 (56%) were excluded from donation. Interestingly, 81 (33.1%) of the ineligible donor candidates were newly diagnosed as having a medical condition that required immediate attention. While 45 (18.5%) candidates were newly diagnosed with diabetes or prediabetes, 12 (4.9%) candidates had hitherto undetected malignancies, 10 candidates (4.1%) cardiac disease, 5 (2.0%) hypertension with end-organ damage, and 4 (1.6%) suffered from kidney disease. The remaining 4 candidates (1.6%) were diagnosed with gastrointestinal diseases, and 1 candidate (0.2%) had an endocrine disorder. CONCLUSION: A comprehensive evaluation process for living kidney donation facilitates the identification of life-changing diagnoses in a significant proportion of candidates, and secures immediate medical attention. This article is protected by copyright. All rights reserved.