Terpenoids represent a large and diverse class of naturally occurring compounds found in a variety of fruits, vegetables and medicinal plants. Structurally some of the terpenoids are similar to human hormones. A diet rich in terpenoids is inversely related with the risk of chronic diseases including cancers. Breast and prostate cancers are hormone-related diseases and the second leading cause of female and male cancer mortality. Diterpenoid paclitaxel, and its semi-synthetic analogue docetaxel, have entered clinical use against established breast and prostate cancers. Here we reviewed potential molecular targets and biological properties of natural terpenoids, including monoterpenoids, diterpenoids, triterpenoids and tetraterpenoids, and their applications in treatment of human breast and prostate cancers. These terpenoids are able to inhibit tumor cell proliferation and induce tumor cell death by inhibiting multiple cancerspecific targets including the proteasome, NF-κB, and antiapoptotic protein Bcl-2. The efficacy of these terpenoids against breast or prostate cancer cells, as demonstrated in pre-clinical studies supports clinical application of these naturally occurring terpenoids in treatment of hormone-related human cancers.