The lysosomal aspartyl protease, cathepsin D, has been suggested to play a role in the metastatic potential of several types of cancer. Cathepsin D is secreted by malignant cells, and is believed to be involved in the breakdown of the extracellular matrix. High levels of active cathepsin D have been found in colon cancer, prostate cancer, uterine cancer and ovarian cancer. Also cathepsin D has recently been associated with the development of Alzheimers disease. Hydroxyethyl isosteres with cyclic tertiary amine have proven to be clinically useful as inhibitors of aspartyl proteases similar to cathepsin D in activity, such as the HIV-1 aspartyl protease. In the present study twenty-eight compounds containing (hydroxyethyl)amine isosteres with cyclic tertiary amines have been synthesized. These compounds show significant activity as cathepsin D inhibitors, many with IC50 values in the nanomolar range. For example, the compounds that contain hydroxyethylamines where the amine is formed from N-piperazine-2-carboxylic acid methyl ester, 4y-bb, show IC50 values ranging from 2.5 to 15 nM.