Millions now suffer the effects of chronic arseniasis related to environmental arsenic exposure. The biological mechanisms responsible for arsenic-induced toxicity and especially chronic effects, including cancer, are not well known. The U.S. Armed Forces Institute of Pathology (AFIP) is participating in an international research effort to improve this understanding by the development of the International Tissue and Tumor Repository for Chronic Arsenosis (ITTRCA). The ITTRCA obtains, archives, and makes available for research purposes, tissues from subjects exposed to arsenic. We provide here a short overview of arsenic-induced pathology, briefly describe arsenic-induced lesions in the skin and liver, and present five case reports from the ITTRCA. Arsenic-induced skin pathology includes hyperkeratosis, pigmentation changes, Bowen disease, squamous cell carcinoma, and basal cell carcinomas. A unique spectrum of skin lesions, known as arsenical keratosis, is rather characteristic of chronic arseniasis. Bowen disease, or squamous cell carcinoma in situ of the skin, has been well documented as a consequence of arsenical exposure. A spectrum of liver lesions has also been attributed to chronic arseniasis. Of these, hepatocellular carcinoma, angiosarcoma, cirrhosis, and hepatoportal sclerosis have been associated with arsenic exposure. We present case reports that relate to these health conditions, namely, squamous cell carcinoma, basal cell carcinoma, and Bowen disease of the skin and hepatocellular carcinoma and angiosarcoma of the liver. Four patients had been treated with arsenical medications for such conditions as asthma, psoriasis, and syphilis, and one case occurred in a boy chronically exposed to arsenic in drinking water.