Inspectors say too many pupils suffer from bullying during their school lives.
A report published today by Estyn also says schools have a responsibility to tackle bullying in all forms under the Education Act 2002, but the ways in which schools deal with bullying varies widely.
'Action on bullying', found that even schools with good strategies to address the problem don't have a common understanding of how important it is to focus on groups of pupils with a higher-than-average risk of being bullied.
They include gay, lesbian and transgender pupils, those with a disability and pupils from a minority ethnic background.
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Wales's largest teaching union welcomed today's results, but says the drop in entries for non-core subjects is still a concern.
The number of pupils achieving A*- C grades has remained at 66.6% for the third year running. The overall pass rate was 98.7%.
Prostate cancer kills over 540 men in Wales every year and more than 2,500 are diagnosed annually.