OUTLINE: Patients undergo leukapheresis prior to study and after final vaccination. Patients are sequentially entered into one of three treatment arms: Arm I: Patients receive an intradermal vaccination of HER-2 derived p369-377 peptide incorporated into polylactide-co-glycolide (PLG) microspheres with adjuvant sargramostim (GM-CSF). Arm II: Patients receive a subcutaneous vaccination of HER-2 derived p369-377 peptide incorporated into PLG microspheres with adjuvant GM-CSF. Arm III: Patients receive a higher dose of subcutaneous vaccination of HER-2 derived p369-377 peptide incorporated into PLG microspheres with adjuvant GM-CSF. Treatment repeats every 4 weeks for up to 6 courses in the absence of unacceptable toxicity.