In preparation for a systematic review of randomised controlled trials of pharmacological and psychological treatments for obsessive compulsive disorder, previously published reviews, which included meta-analyses, were rated by quality features. Nine published and unpublished reviews were identified. All were found to have major deficiencies. Of particular concern are the poor descriptions of how individual trials were identified, included or excluded; absence of investigation of sources of heterogeneity; and the universal lack of measures of methodological quality of studies. Systematic reviews of treatments for obsessive compulsive disorder must grapple with the problems of diverse outcome measurements, which are usually continuous. An outline will be given of the proposed systematic review, which will adhere to Cochrane Collaboration guidelines.