OBJECTIVE Vitamin D deficiency is a common problem in the general population. A high frequency of vitamin D deficiency in the pre-dialysis and dialysis populations has been observed overseas, but there is limited information regarding vitamin D levels in Australian dialysis patients. METHODS We measured 25-hydroxyvitamin D levels in 120 haemodialysis (HD) and 31 peritoneal dialysis (PD) patients. We defined vitamin D deficiency as a level <50 nmol/L and insufficiency as a level of 50-74 nmol/L. We assessed for correlation between vitamin D levels and markers of bone and mineral metabolism, age, sex, dialysis type, dialysis duration, haemoglobin and erythropoietin dose. RESULTS Of the HD patients, 59 (49%) were frankly deficient and 39 (33%) had insufficiency. Of the PD patients, 24 (77%) were frankly deficient and 6 (19%) had insufficiency. Overall, only 23 patients (19%) had sufficient levels of vitamin D. Vitamin D levels were significantly lower in PD patients (P = 0.001), in females (P = 0.002) and in those with diabetic nephropathy (P = 0.03). There was no correlation between vitamin D levels and markers of bone and mineral metabolism, age, dialysis duration, haemoglobin or erythropoietin dose. CONCLUSIONS Vitamin D deficiency and insufficiency were very common in this cohort of prevalent Australian dialysis patients. Lower levels were associated with PD as treatment modality, female sex and diabetic nephropathy.