To minimize the health risks faced by living kidney donors, multiple clinical practice guidelines have been developed on the assessment and care of potential donors. This study aims to compare the quality, scope, and consistency of these guidelines. We searched for guidelines on living kidney donation in electronic databases, guideline registries, and relevant Web sites to February 21, 2011. Methodological quality was assessed using the Appraisal of Guidelines for Research and Education (AGREE) instrument. Textual synthesis was used to compare guideline recommendations. Ten guidelines, published from 1996 to 2010, were identified. Although generally comprehensive, scope varied considerably and mostly appeared to lack methodological rigor. Many recommendations were consistent, but important differences were evident, particularly for thresholds for comorbidities which precluded donation; obesity/overweight (body mass index, 30-35 kg/m), diabetes/prediabetes (fasting blood glucose level, 6.1-7.0 mmol/L and oral glucose tolerance test, 7.8-11.1 mmol/L), hypertension (130/85 to 140/90 mm Hg), cardiovascular disease, malignancy, and nephrolithiasis. The importance of informed voluntary consent, genuine motivation, support, and psychological health were recognized but difficult to implement as specific tools for conducting psychosocial assessments were not recommended. Multiple major guidelines for living kidney donation have been published recently, resulting in unnecessary duplicative efforts. Most do not meet standard processes for development, and important recommendations about thresholds for exclusion based on comorbidities are contradictory. There is an urgent need for international collaboration and coordination to ensure, where possible, that guidelines for living donation are consistent, evidence based, and comprehensive to promote best outcomes for a precious resource.