Long term storage stable daptomycin-containing compositions are disclosed. The compositions include daptomycin or a pharmaceutically acceptable salt thereof at a concentration of less than or equal to about 25 mg/mL, a buffer having an acidic functional group and have a pH of from about 6.0 to about 7. The formulations are surprisingly free of degradation products such as the hydrolysis product of daptomycin and the β-isomer of daptomycin after storage periods of at least about 18 months.
