Water supply has become insufficient for the rapidly rising population in Pakistan. As in other parts of Pakistan, coastal villagers also become helpless to use ground water for drinking and daily consumption, due to their need and their not knowing about the quality of water. A number of patients arrived to Karachi hospitals, suffering from a strange disease and this study has been done to find the exact cause of this disease by assuming that arsenic contaminated drinking water may be one of the possibilities. Maximum permissible limit (MRL) of arsenic in drinking water of Pakistan has been calculated by analysis of 50 samples of supply water as 0.05 mg/l. It was observed that most of the residents of Ibrahim Hyderi, Rehri, Chashma, Mubarak, Fagheer Muhammad and Gul Hasan Goths (villages) of the coastal belt of the Karachi city were suffering from melanosis, leuco-melanosis, keratosis, hyperkeratosis, dorsum, non-pitting oedema, gangrene and skin cancer that might be due to arsenic contamination in drinking water. Studied subjects were seriously affected due to paralyzing lower limbs, arms and other body parts in the coastal belt of Karachi, which was observed to be the most prominent health hazards of arsenic. The majority of victims were children. This community problem demands proper addressing and extensive research for improving the quality of life of these villagers.