Rickets is reported in a 19 year old white man with cystic fibrosis in whom pancreatic and hepatic involvement was advanced. There was evidence of secondary hyperparathyroidism with proximal renal tubular acidosis, aminoaciduria, phosphaturia and hypophosphatemia. Treatment with oral pancreatic and parenteral vitamin D supplements led to full recovery of the rachitic syndrome and the proximal renal tubular dysfunction.