The H11-CAG-MerCreMer mouse is a tamoxifen-inducible mouse that ubiquitously expresses the MerCreMer recombinase under the control of the CAG promoter. Compared to Cre recombinase fused with a single estrogen receptor (CreMer or CreERT), the double ER-fusion Cre recombinase (MerCreMer) exhibits higher Cre recombinase activity and less expression leakage. In the absence of tamoxifen, MerCreMer recombinase remains in the cytoplasm. Upon tamoxifen treatment, the recombinase translocates into the nucleus to exert its recombination function. When crossed with mice harboring loxP sites, the offspring will undergo Cre-mediated recombination between loxP sites in systemic tissues after tamoxifen induction. This strain is homozygous viable.