The present invention relates to new thiolalkyl benzoic acids, pharmaceutical compositions and diagnostic kits comprising such compounds, and methods of using such compounds for inhibiting NAALADase enzyme activity, detecting diseases where NAALADase levels are altered, effecting neuronal activity, effecting TGF-.beta. activity, inhibiting angiogenesis, and treating glutamate abnormalities, neuropathy, pain, compulsive disorders, prostate diseases, cancers, glaucoma, retinal disorders, and cancer.