Islam is the main religion of the citizens of Kuwait and the majority of Kuwait's citizen population is Muslim; there are no official figures, but it is estimated that 60-70% are Sunni and 30-40% are Shias.
Some other minor Muslim sects do exist in Kuwait's society, but in very small or rare numbers. There are no estimates of the number of non-citizen Muslims.
In 2001, there were 525,000 Sunni Kuwaiti citizens, 300,000 Shia Kuwaiti citizens and 820,000 Kuwaiti citizens in total thus Sunnis formed 64% and Shias formed 36.5% of the Kuwaiti citizen population. In 2002, the US Department of State reported that Shia Kuwaitis formed 30%-40% of Kuwait's citizen population, noting there were 525,000 Sunni Kuwaiti citizens and 855,000 Kuwaiti citizens in total (61% Sunnis, 39% Shias). In 2004, there were 600,000 Sunni Kuwaitis citizens, 300,000-350,000 Shia Kuwaiti citizens and 913,000 Kuwaiti citizens in total. In 2008, the Strategic Studies Institute reported similar figures.