This study aimed to shed light on the long-term current state and variations of Lake Manzala water quality by some chemical, physical, and biological properties as: temperature, pH, total solids, hardness, sodium, chlorides, total nitrogen, total phosphorous, dissolved oxygen, biological oxygen demand, chemical oxygen demand, iron, manganese, total bacteria count, and faecal coliform count. Comparing results obtained with the limit of the Environmental Protection Agency for water body health showed the following: The mean of temperature and pH are within the permissible limits. Manganese is almost within the permissible limits, but in 2005, it was slightly above the permissible limit. The mean of total solids, hardness, biological oxygen demand, chemical oxygen demand, sodium, chloride, total nitrogen, total phosphorus, Iron are above the permissible limit. In some years, the dissolved oxygen is below the permissible limit. The results obtained will be useful for the optimal management of Lake Manzala as well as for a better view of its current situation.