The solubilities of the disodium salt hemiheptahydrate of ceftriaxone in different concentrations of methanol in water at (25, 35, and 45) degreesC are measured by using a gravimetrical method. The densities of the saturated solution are also determined with a digital densimeter (Anton Paar, model DMA 45) at corresponding temperatures. The solubility of the disodium salt hemiheptahydrate of ceftriaxone increases with increasing temperature but decreases with increasing concentration of methanol in the solution.