Single cell analysis by flow cytometry is a powerful modality for analyzing the expression of a set of molecules. Nevertheless, the most significant deficiency of this technology has been the poor sensitivity of flow cytometry compared to other techniques such as immunoblotting. In order to address this deficiency, we have developed an enzymatic amplification system for flow cytometry that enhances the specific signal by 10-100-fold. Using enzymatic amplification staining (EAS), we and others have been able to assess the expression of molecules that could not be detected otherwise. In this review, we show the capability of this new technology to detect specific RNA expression.