Injectable vitamin D agents are commonly used to manage secondary hyperparathyroidism in dialysis patients. Yet, there are few data documenting the trends and geographic variations in the use of these agents in large, representative samples. We sought to describe patterns and variations in the use of vitamin D formulations (calcitriol, paricalcitol, and doxercalciferol) in hemodialysis patients. We studied patients in the United States Renal Data System between January1999 and December 2008 with Medicare as a primary payer. Annual percentages of patients treated with each type of formulation were tabulated by race, sex, and age at dialysis initiation. The geographical distribution of vitamin D dose per patient was mapped at the state level. Intravenous vitamin D use has increased sharply from 1999 to 2008 with 83.9% of patients treated with any vitamin D formulation in 2008. The use of calcitriol has declined since 1999, going from being administered in 58.6% of patients in 1999 to 1.8% in 2008. Paricalcitol was found to be the overwhelmingly preferred formulation during the study years. In 2008, the average dose among black patients was 84% greater than among white patients (136 mcg vs. 73.6 mcg). Higher doses of vitamin D were administered to patients in the southern region of the country. Vitamin D use has increased and parallels the rise in use of paricalcitol and doxercalciferol. Given the variations in use and known pharmacologic differences in vitamin D formulations, future research should focus on whether the formulations differentially affect patient outcomes.