Asia has the world's largest share of children not receiving an education, says a report by the United Nations educational organisation, Unesco.
In Asia 28m girls and 18m boys do not attend primary school
Despite increased enrolment rates, 46 million primary school-age children in the region are out of school, it said.
That is 45% of the global total of youngsters not attending school.
The report did not give a specific reason for the drop-out rate but it did say it could be linked to learning difficulties and poor teacher training.
Across the world, about 104 million children do not go to school, Unesco said.
The research was based on educational data for the 2000/2001 school year from 22 Asian nations.
The area covered by the report stretches from China to East Timor and from Iran to the Philippines.
The quality of education varied widely across the region, the report's authors found.
PRIMARY SCHOOL DROP-OUT RATES
India - 53%
Laos - 47%
Burma - 45%
Nepal, Cambodia, Bangladesh - 35-38%
Boys and girls in east Asia got the best staffing levels, with one teacher for every 21 pupils in primary school.
That compared with one teacher for every 40 children in south and west Asia.
Bangladeshi pupils were in the most crowded classes, with just one teacher for every 57 pupils.
"In order to decrease the numbers of children out of school, countries in south and west Asia will need to recruit a very large number of qualified teachers," the study said.
Of all the countries studied, Malaysia devoted the
highest percentage of its GDP to education, with 6.2%.
At the other end of the scale, Burma spent just 1.4% of its GDP on schooling.