The effects of music therapy, or music therapy added to standard care, compared to placebo, standard care or no treatment for people with serious mental illnesses such as schizophrenia were reviewed. The Cochrane Schizophrenia Group’s Register (July 2002) was searched. This was supplemented by hand-searching of music therapy journals, manual searches of reference lists and contacting relevant authors. All RCTs were included that compared music therapy with standard care or other psychosocial interventions for schizophrenia. Studies were reliably selected, quality assessed and data extracted. Data were excluded where more than 30% of participants in any group were lost to follow up. Non-skewed continuous endpoint data from valid scales were synthesised using a standardised mean difference (SMD). If statistical heterogeneity was found, treatment ‘dosage’ and treatment approach were examined as possible sources of heterogeneity. Four studies were included. These examined the effects of music therapy over the short to medium term (1 to 3 months), with treatment ‘dosage’ varying from 7 to 78 sessions. Music therapy added to standard care was superior to standard care alone for the global state. Continuous data suggested some positive effects on general mental state, on negative symptoms and social functioning. However, these latter effects were inconsistent across studies and depended on the number of music therapy sessions. All results were for the 1–3-month follow-up.