The restricted diets of patients with chronic renal insufficiency (CRI) can lead to inadequate intake of some vitamins. We studied thiamin, riboflavin and pyridoxine nutritional status of CRI subjects on unrestricted or low-protein diet. Results show that riboflavin status is inadequate even before the beginning of the follow up and worsens with time for both groups, while thiamin and pyridoxine status becomes inadequate in some patients after a long period on the low-protein diet. Water-soluble vitamin supplements could improve the nutritional status of CRI patients on protein-restricted diet.