BACKGROUND: Music therapy (MT) aims at maintaining, restoring and furthering physical/emotional/mental health. This review assesses effectiveness of MT and its methods for autism spectrum disorder (ASD), dementia, depression, insomnia and schizophrenia. METHODS: A search for systematic reviews and health technology assessment reports was conducted and yielded 139 hits. Given the large amount, we focused on five frequent diagnostic groups with available Cochrane reviews. A second search was conducted in four databases. Two authors independently performed study selection, data extraction and assessed methodological quality. Only trials with moderate/low risk of bias (RoB) were selected. RESULTS: Ten randomized controlled trials (1.248 participants) met inclusion criteria. For schizophrenia, no studies with low/moderate RoB were found; therefore, updating was not possible. The Cochrane authors stated that quality of life (QoL), social functioning, global/mental state improved for schizophrenia, but not global functioning. For ASD, MT improved behaviour, social communication, brain connectivity and parent-child relationship. For depression, mood was enhanced, and for insomnia, sleep quality, stress, anxiety, total sleep time, disease severity and psychological QoL improved. MT positively affected mood, neuropsychiatric behaviour, apathy, communication and physical functions for dementia; behavioural/psychological symptoms improved only in severe, and memory and verbal fluency only in mild Alzheimer's disease. Cognition improved for dementia in one of four studies. Both active (playing music) and receptive (listening to music) methods were used for dementia, whereas for ASD and depression, active methods were applied. For insomnia, only receptive methods were used. CONCLUSION: These findings provide evidence that MT helps patients improving their physical/psychosocial health. More research investigating long-term effects is needed.