The Nephrology Nursing Certification Review Guide (5th edition) was written as a resource for nephrology nurses during their preparation for certification. This guide can be used for both the Certified Nephrology Nurse (CNN) and the Certified Dialysis Nurse (CDN) exams based on the blueprint from the Nephrology Nursing Certification Commission (NNCC). This edition includes a rationale for each answer. When possible, a reference has been pro vided; if a reference was not available, the answer was based on expert opinion. We also included a section for the Advanced Practice Registered Nurse in Nephrology focused on pharmacology and diagnosis.