Hardly any research is available on the patterns of irregular migration in the Gulf countries, home to about 23 million migrant workers and their families. The objective of this paper is to briefly document the volume and types of irregular migration in the region and to evaluate the response of irregular migrants to recent amnesty programmes in Kuwait and Saudi Arabia for regularising their stay or facilitating their departure. Irregular migrants in Kuwait were defined as those overstaying their residence, visit, or other visa. In Saudi Arabia, they were defined as those overstaying their visa, working for someone other than their sponsor, or in an occupation that did not match their work permit. Of the 124,000 irregular migrants in Kuwait in 2011, only 37 percent departed or regularised their stay while the rest remained in the country illegally. Bangladeshis were the largest group among irregular migrants, followed by Egyptians and Indians. In Saudi Arabia in 2013, about one million irregular migrants availed the amnesty to depart while more than 4 million regularised their stay. The scale of regularisation was very large and is likely to have exerted major impact on the structure and functioning of the Saudi labour market. Some reasons for the low compliance with amnesty, especially in Kuwait, are discussed and suggestions are offered for increasing such compliance in future.