Arsenic has been used as a medicine for thousands of years. In the late 19th century it was administered as a treatment for syphilis. Early in this century, arsenic was commonly prescribed for certain types of leukemia; however, its use in hematological disorders died out in the 1930s with the advent of radiotherapy. At present, its only medical indication is for African sleeping sickness. But recent studies have revived interest in arsenicals as treatment for acute promyelocytic leukemia (APL), according to speakers at the Chemotherapy Foundation Symposium XVI [New York City, US; Nov, 1998].