Since 1990, a large number of people have been experiencing various health problems from drinking arsenic contaminated water (50-1860 microg/L) in 13 counties of Inner Mongolia, China, most of which are located in the Hetao Plain area. It is calculated that 411,243 people are currently at risk from arsenic poisoning. Clinical and epidemiological investigations were carried out on 13,021 people to ascertain the nature and degree of morbidity that occurred due to chronic arsenic toxicity. In all of the studied patients, 22% had typical hyperkeratosis on the palms or soles and some had raindrop-like hyperpigmentation and depigmentation on the trunk. Other data recorded included subjective and objective symptoms, such as chronic cough (35.0%) and insomnia (37.5%). During physical checkups of 680 villagers in arsenic affected areas, liver function tests showed elevated globulin levels in 6.8% (P value=0.006) of the subjects. Neurotoxicity manifesting as loss of hearing 5.88 (P value=0.005), loss of taste 5.44% (P value=0.001), blurred vision 17.35% (P value=0.000), tingling and numbness of the limbs 33.53% (P value=0.000) and hypertension 8.09% (P value=0.000) were significantly higher in the arsenic affected villages and arsenic pollution also seemed to affect patients' social life and mental health. To solve the problem of arsenic exposure, the quality of drinking water needs to be improved by reducing the arsenic content. We also plan to carry out a survey to detect the incidence and types of cancer among this population.