Long term storage stable daptomycin-containing compositions are disclosed. The compositions include a pharmacologically acceptable fluid including daptomycin or a pharmaceutically acceptable salt thereof at a concentration of less than or equal to about 25 mg/mL, and a calcium source. The formulations are surprisingly free of degradation products such as the hydrolysis product of daptomycin, the &bgr；-isomer of daptomycin and anhydro daptomycin after storage periods of at least about 18 months under refrigerated conditions.
