Objective: To describe the association of calcitriol treatment with the change in parathyroid hormone (PTH) and biochemical markers of bone disease in infants with metabolic bone disease of prematurity (MBD) and secondary hyperparathyroidism. Study design: This retrospective chart review examined serum intact PTH, serum calcium (Ca), serum phosphorus (P), serum alkaline phosphatase (APA), urine calcium/creatinine (UCa/Cr), and tubular reabsorption of phosphate (TRP) in 32 infants prior to and following calcitriol treatment for MBD with PTH >100 pg/ml. 25-hydroxyvitamin D concentrations were recorded. Results: Following calcitriol treatment, PTH decreased from median (min/max) 220 (115/593) to 25 (3/259) pg/ml, p < 0.001; Ca increased from 9.9 (8.9/10.7) to 10.3 (9.7/11.3) mg/dl, p < 0.001; P increased from 4.3 (2.7/6.4) to 5.4 (2.9/7.4) mg/dl, p = 0.001; and TRP increased from 81 (59/98) to 91.5 (78/98) %, p = 0.03. APA did not differ pre-treatment: 616 (209/1193) vs. post-treatment 485 (196/1229) U/L, p = 0.12. Vitamin D deficiency was not present. Hypercalcemia with hypercalciuria occurred in 3/32 subjects, all normalized after dose reduction. Conclusion: Improvements in MBD markers and lack of serious adverse effects suggest calcitriol may be a treatment option in infants with MBD and secondary hyperparathyroidism.