This invention is directed towards a ready-to-use aqueous composition of fludarabine phosphate. In one embodiment, the invention is directed to an aqueous fludarabine phosphate composition which comprises fludarabine phosphate, a base, and water. The concentration of fludarabine phosphate in the composition may be between about 0.5 mg/mL and about 50 mg/mL. The pH of the composition may be between about 5.5 and about 7.1.