The Army is dismissing the equivalent of almost a battalion of soldiers every year for taking drugs, a report says.
The Royal United Services Institute said the number of positive tests for illegal drugs, like ecstasy and heroin, rose from 517 in 2003 to 769 last year.
Positive tests for cocaine use rose four-fold during the same period. A dishonourable discharge is likely after a positive test for illegal drug use.
The MoD said drug abuse was less common among forces personnel than civilians.