Introduction
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During hemodialysis, contact between blood and dialysis membranes leads to complement and neutrophil activation.  This effect is known as bioincompatibility and is most pronounced with older, less expensive, cellulose-based membranes.  However, there is considerable controversy as to whether synthetic (more biocompatible) dialysis membranes improve survival in patients with acute renal failure (ARF) compared to cellulose-based membranes.  Numerous trials have been conducted but have yielded conflicting results.  Although the discordant results of existing studies could be explained by the varying degrees of biocompati-bility among the different membranes used, these studies were also of low statistical power.  Thus we sought to determine whether combining results from all published trials would provide a better estimate of the effect of membrane on survival in ARF. 

Methods
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Studies were identified through a Medline search, authors\' files and bibliographies of review articles.  Studies were included if they were done prospectively, compared synthetic and cellulose-based membranes, and specified mortality rates for each group.  Results were expressed as the cumulative odds ratio (OR) of survival over time where a *P* \< 0.05 was considered significant.  The entire sample was then analyzed for homogeneity using a Mantel--Haenszel (M--H) test, the OR recalculated using the weights from the M--H test and final M--H combined odds ratio determined. 

Results
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Eight prospective studies were included (*n* = 857) and an improvement in survival with biocompatible membrane was demonstrated (OR = 1.37, 95% CI = 1.03--1.84, *P* = 0.03). 

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Conclusion
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Use of biocompatible membranes for dialysis in ARF is associated with improved patient survival compared to the use of bioincompatible dialysis membranes.