background The 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (dsm) was published in May, 2013. aim To review the changes in the diagnostic criteria for autism spectrum disorder (asd) and adhd in dsm-5, compared to dsm-iv. method The diagnostic criteria for asd and adhd in dsm-iv and dsm-5 are compared. The new diagnostic criteria are summarised and relevant literature is discussed. results The new category asd includes the majority of the pervasive developmental disorders; however, in dsm-5, patients without stereotypical patterns of behaviour or interests will, from now on, be classified as having Social Communication Disorder. The threshold for meeting the diagnostic criteria for adhd has been lowered slightly. However, this is supported by clinical and epidemiological data and is unlikely to result in over-diagnosis. conclusion Research into subtypes of asd may stagnate as a result of the changes introduced in dsm-5. For clinicians, the diagnostic criteria for asd and adhd may be more clear-cut and possibly more user-friendly than the diagnostic criteria for these disorders as given in dsm-iv.