VIP receptors were investigated in breast cancer biopsy specimens. Twenty biopsy specimens bound 125I-VIP with high affinity. Also, each of the 20 biopsy specimens had high amounts of VPAC1 receptor mRNA. MCF-7 cells have VPAC1 receptors that bound the VIP chemotherapeutic conjugate, (Ala2,8,9,19,24,25,27 Nle17, Lys28)VIP-L2-camptothecin, with high affinity. VIP chemotherapeutic conjugates may be useful agents to inhibit the growth of breast cancer.