Approximately half of all patients with metastatic cancer develop a malignant pleural effusion which is likely to lead to a significant reduction in quality of life secondary to symptoms such as dyspnoea and cough. The aim of pleurodesis in these patients is to prevent re-accumulation of the effusion and thereby of symptoms, and avoid the need for repeated hospitalization for thoracocentesis. Numerous clinical studies have been performed to try to determine the optimal pleurodesis strategy, and synthesis of the available evidence should facilitate this.The aims of this review were to ascertain the optimal technique of pleurodesis in cases of malignant pleural effusion; to confirm the need for a sclerosant; and to clarify which, if any, of the sclerosants is the most effective.The Cochrane Central Register of Controlled Trials was searched for studies on 'pleurodesis'. Studies for inclusion were also identified from MEDLINE (1980 to June 2002) and EMBASE (1980 to May 2002). No language restriction was applied.RCTs of adults subjects undergoing pleurodesis for pleural effusion in the context of metastatic malignancy (or a malignant process leading to pleural effusion) were included.Two reviewers independently selected studies for inclusion in the review, and extracted data using a standard data collection form. Primary outcome measures sought were effectiveness of pleurodesis as defined by freedom from recurrence of effusions, and mortality after pleurodesis. Secondary outcomes were adverse events due to pleurodesis. Dichotomous data were meta-analysed using a fixed effect model and expressed as relative risk. The number-needed-to-treat (NNT) was calculated for pleurodesis efficacy. In addition, for adverse events, the overall percentage of patients across studies exhibiting a particular adverse effect such as fever, pain, or gastrointestinal symptoms was calculated.A total of 36 RCTs with 1499 subjects were eligible for meta-analysis. The use of sclerosants (mitozantrone, talc and tetracycline combined)compared with control (instillation of isotonic saline or equivalent pH isotonic saline or tube drainage alone) was associated with an increased efficacy of pleurodesis. The relative risk (RR) of non-recurrence of an effusion is 1.20 (95% CI 1.04 to 1.38) in favour of the use of sclerosants based on five studies with a total 228 subjects. Comparing different sclerosants, talc was found to be the most efficacious. The RR of effusion non-recurrence was 1.34 (95% CI 1.16 to 1.55) in favour of talc compared with bleomycin, tetracycline, mustine or tube drainage alone based on 10 studies comprising 308 subjects. This was not associated with increased mortality post pleurodesis. The RR of death was 1.19 (95% CI 0.08 to 1.77) for talc compared to bleomycin, tetracycline, mustine and tube drainage alone based on six studies of 186 subjects. Death was not reported in all studies and, when reported, was attributed to underlying disease, only one death being reported as procedure-related. In the comparison of thoracoscopic versus medical pleurodesis, thoracoscopic pleurodesis was found to be more effective. The RR of non-recurrence of effusion is 1.19 (95% CI 1.04 to 1.36) in favour of thoracoscopic pleurodesis compared with tube thoracostamy pleurodesis utilizing talc as sclerosant based on two studies with 112 subjects. Comparing thoracoscopic versus bedside instillation (with different sized chest tubes) of various sclerosants (tetracycline, bleomycin, talc or mustine) the RR of non-recurrence of effusion is 1.68 (95% CI 1.35 to 2.10) based on five studies with a total of 145 participants.Adverse events were not reported adequately to enable meta-analysis.The available evidence supports the need for chemical sclerosants for successful pleurodesis, the use of talc as the sclerosant of choice, and thoracoscopic pleurodesis as the preferred technique for pleurodesis based on efficacy. There was no evidence for an increase in mortality following talc pleurodesis.