In recent years, growing interest has been focused on the field of chemoprevention using natural therapies. The reason to turn toward "natural" remedies is associated with diverse beneficial pharmacological properties of natural compounds. Isothiocyanates (ITCs), the major pharmacological active constituents of cruciferous vegetables, are derived from the enzymatic hydrolysis of glucosinolates (GSLs). ITCs govern many intracellular targets including cytochrome P 450 (CYP) enzymes, proteins involved in antioxidant response, tumorigenesis, apoptosis, cell cycle, and metastasis. Investigation of the mechanisms of anti-cancer drugs has given important information regarding the use of natural chemopreventive compounds. This extensive review covers various molecular aspects of the interactions of ITCs with their recognized cellular targets involved in cancer treatment in order to enhance anti-tumor outcome with decreased toxicity to patients.