The use of monoclonal antibodies to the angiotensin-II type-I receptor is provided for the treatment of cancer and vascular smooth muscle cell proliferation. Specifically, use is provided of a monoclonal antibody or a fragment thereof to a peptide comprising the N-terminal portion of the angiotensin-II type-1 receptor defined by the sequence MILNSSTEDG IKRIQDDCPK AGRHNYIFVM IPTLYSIIFV VGIFG in the preparation of a medicament for the treatment of cancer or in the preparation of a medicament for the treatment of vascular smooth muscle (VSM) cell proliferation.