We present a study of the X-ray emission from binary systems extracted from the Lindroos catalogue ( Lindroos 1986 ) based on the ROSAT All-Sky survey as well as ROSAT PSPC and HRI pointings .
The studied sample consists of visual binary systems comprised of early-type primaries and late-type secondaries .
The ages of the systems were determined by Lindroos ( 1985 ) from uvby \beta photometry of the primaries .
These ages range between 33 and 135 Myr , so if the late-type secondaries are physically bound to the early-type primaries , they could be Post-T Tauri stars ( PTTS ) .

We have found strong X-ray emission from several secondaries .
This fact together with their optical and IR data , make them bona fide PTTS candidates .
We have also detected X-ray emission from several early-type primaries and , in particular , from most of the late-B type stars .
Because their HRI hardness ratios are similar to those from resolved late-type stars , the presence of an unresolved late-type companion seems to be the cause of this emission .