This invention relates to a method for preparing azithromycin dihydrate from crude azithromycin by the gradual crystallization of azithromycin from acetone by the addition of a minimal amount of water to effect crystal formation is disclosed. This invention also relates to a method of making azithromycin from desmethyl-azithromycin by dissolving desmethyl-azithromycin in acetone, adding activated carbon, adding formaldehyde, adding formic acid; refluxing the desmethyl-azithromycin acetone solution, adding sodium hydroxide to induce precipitation of azithromycin, and isolating azithromycin.