Background: MicroRNAs (miRNAs) represent important post-transcriptional regulators with a dynamic expression profile during health and disease. Objectives: We explored the miRNA profile of human mast cells (MCs) during sen­sitization with IgE, during activation through IgE, and relat ed it to prostaglandin D₂ synthesis and histamine release. Method: We investigated the expression pattern of 762 miRNAs during the IgE-mediated sensitization and activation of MCs cultured from CD133+ stem cells that were isolated from allergic asthmatic patients and nonatopic controls. Results: IgE-mediated sensitization increased the expression of miRNA-210 eight-fold. This increase was sustained during IgE-mediated MC activation. Furthermore, we confirmed the increase of the miRNA-132/212 cluster after MC activation. Predicted target genes of miRNA-210/132/212 were enriched in several pathways known to be involved in MC activation. Histamine release was significantly higher in MCs from allergic patients when compared to controls, and a number of miRNAs correlated with histamine release and prostaglandin D₂ synthesis during MC activation. Conclusion: The miRNAs and analysis presented here can help to elucidate the role of miRNAs in mediator release during MC activation. We speculate that miRNA-210 could be important in MC sensitization that leads to allergic symptoms.