The Mood and Feelings Questionnaire (MFQ) was designed to detect clinical depression in children and adolescents. Our aim was to investigate the relationship between symptom scores obtained using the short-version MFQ and psychiatric disorders in a non-clinical sample. Seventy-eight parents and 71 twins, who had completed the MFQ, were interviewed separately using a semistructured diagnostic interview, the Child and Adolescent Psychiatric Assessment. Parent-rated MFQ scores (MFQ-P) were found to distinguish those with ICD-10 (point biserial correlation = 0.345) and DSM-III-R depression (point biserial correlation = 0.369) from non-depressed cases. MFQ-P scores also differentiated depressed cases from those with 'other psychiatric diagnoses' (any anxiety disorder, oppositional defiant disorder and conduct disorder, hyperkinetic disorder/attention deficit hyperactivity disorder and adjustment disorder/post-traumatic disorder). The MFQ-P at the chosen cut-off point showed a sensitivity of 0.75 and specificity of 0.73 for an ICD-10 diagnosis of depression and a sensitivity of 0.86 and specificity of 0.87 for DSM-III-R depression. The number of self-rated reports (MFQ-C) was small, but overall the results suggest that self-rated MFQ scores may show less specificity. The MFQ-C at the selected cut-off point showed a sensitivity of 0.6 and specificity of 0.61 for ICD-10 depression, and a sensitivity of 0.75 and specificity of 0.74 for DSM-III-R depression.