The stability of dilute iron dextran formulations and of one formulation in parenteral nutrient solutions was studied. Seven formulations for dilute (50 mg/dl) iron dextran solutions and four parenteral nutrient solutions containing 100 mg/liter of iron dextran were prepared. Total iron and free ferrous ion content of the preparations were measured for: (1) the dilute solutions at monthly intervals after up to three months of storage at room temperature and under refrigeration and (2) the parenteral nutrient solutions after 18 hours of storage at room temperature. Four of the seven dilute solutions were stable after two months of storage. The easiest-to-prepare dilute solution (iron dextran, benzyl alcohol, and sterile water for injection) was stable for three months; stability was greater when refrigerated. Iron dextran was stable in the four parenteral nutrient solutions after 18 hours of room-temperature storage. The study suggests that addition of recommended daily doses of iron dextran to parenteral nutrient solutions creates no stability problems; however, further study of the effects of temperature, pH, light, and storage time are recommended.