Purpose – The purpose of this paper is to analyze the impact of applying alternative Shariah screens on the resulting universe of halal assets and to show that Shariah screening procedures currently used in practice are inconsistent with respect to discriminating between halal and haram. Design/methodology/approach – An empirical data analysis of the different asset universes obtained when applying the criteria specified by the most prominent Shariah-compliant funds and indexes to a common standard asset universe, the assets contained in the S&P 500 index. Findings – Analysis reveals that the asset universes are significantly different in size as well as constituents, i.e. for every index there is a substantial number of assets which are specified as halal or haram but classified the opposite way for other indexes. This indicates that, so far, there is no universal or generally accepted understanding of how to transform the descriptive Shariah rules into a system of checkable investment guidelines. Research limitations/implications – The results presented in this paper could motivate the development of a standardized screening framework which, taking into account the existing Shariah guidelines, produces a controlled, unified and understandable classification of assets, by which the credibility and consistency of Islamic equity products is enriched. Practical implications – Islamic institutions and Shariah scholars are guided to set up a common and standardized Shariah screening norm based on which computer-based management systems for Shariah compatible portfolios could be developed. Originality/value – This paper is believed to be the first empirical comparative analysis identifying the impact of using different Shariah screens on the composition of the compliant asset universe. The sensitization of Shariah scholars, fund managers and Islamic investors for the consequences of this so far undiscovered relation will certainly contribute to an enrichment of the credibility and consistency of Islamic equity products.