BACKGROUND Few controlled studies have compared nail disorders in patients with chronic renal failure (CRF) and haemodialysis (HD)-dependent individuals with a healthy population. OBJECTIVE The aim of this study was to compare the prevalence of nail disorders in patients with CRF and patients undergoing HD treatment with a healthy population, and evaluate the relationship between nail changes and various demographic, medical and laboratory parameters in these groups. METHODS In this case-control study we recruited 73 patients affected with CRF, 77 patients undergoing regular HD and 77 healthy individuals. All patients were examined for the presence of nail disorders. Various parameters [age, gender, type of kidney disease, regular medications, duration of renal failure and HD, dialysis efficacy (Kt/v), haemoglobin, neutrophil count, calcium, phosphorus, albumin, creatinine, urea, alkaline phosphatase and parathyroid hormone (PTH) levels] of the patients were determined by multivariate analysis and compared. RESULTS Forty-four patients (60.3%) with CRF and 48 patients (62.3%) undergoing HD treatment had at least one type of nail pathology. The most common nail alterations found in patients with CRF and those undergoing HD were absence of lunula (AL) and half-and-half nails (HHN), respectively. Prevalence of nail disorders among patients with CRF was influenced significantly by PTH level (P = 0.03). In the HD group, male sex, age above 65 years and comorbidities (diabetes mellitus, hypertension and heart failure) were significantly associated with nail pathologies. CONCLUSIONS Patients with CRF and those undergoing HD therapy have higher rates of nail disorders when compared to a healthy population. Efficient HD does not improve nail changes.