Toxins identified as causing parkinsonism and being related to overall idiopathic Parkinson disease risk range from heavy metals to pesticides to contaminants in synthetic heroin. Several described in this article exhibit significant oxidative stress on neurons of the central nervous system and have a particular predilection toward damage of dopaminergic neurons. Although many of these toxins have well-established connections with Parkinson disease risk, a few continue to be studied with data still being produced. The parkinsonisms caused by these agents have variable responses to dopaminergic therapies. This article discusses manganese, mercury, MPTP, organochlorines, organophosphates, paraquat, rotenone, and Agent Orange.