A sustained release microsphere composition comprising-- (i) microspheres comprising (A) a biodegradable polymer which is a homopolymer of lactic acid or a copolymer of lactic acid and glycolic acid having a monomer ratio in the range of about 1:1 to about 3:1, and (B) a therapeutically effective amount of octreotide acetate, and (ii) pharmaceutically acceptable excipients,which when injected, delivers octreotide acetate, for a period of at least one month.