Statistics published yesterday (Thursday) show that the percentage of boys at that stage who read during dinner time, playtime, or in the evening has fallen from 29 per cent in 1997 to 17 per cent in 2002.
The fall comes despite a dramatic increase in the proportion of pupils leaving primary school able to read or write well since the mid-1990s - a success ministers attribute to the introduction of the national literacy strategy south of the border in 1998. However, boys still lag behind girls in reading and a series of projects has been set up to tackle the problem.
The new statistics on boys' reading habits come from an annual survey of 10-15s by the respected Schools Health Education Unit (SHEU) in Exeter.
David Regis, the unit's research manager, said a connection could be drawn between the drop in boy readers and the national literacy strategy.
The national strategy has come under renewed fire in recent weeks from authors, including Philip Pullman, who say that it has stopped children taking pleasure in reading.
However, Dr Regis said that other data from the unit's survey of 37,150 young people showed that many leisure interests were competing for children's time and that reading remained popular with girls.
Boys listed their favourite leisure activities as watching television, playing computer games, meeting with friends and taking part in sport.