Lyophilized recombinant human leptin N82K mutant although stable at room temperature for several weeks, should be stored desiccated below -18 degree C. Upon reconstitution at > 0.1 mg human leptin per ml and up to 2 mg and filter sterilization recombinant human leptin N82K mutant can be stored at +4 degree C or even room temperature for several weeks. At lower concentration addition of a carrier protein (0.1% HSA or BSA) is suggested. Please prevent freeze-thaw cycles.