Metacaspase is discovered gene family with distant caspase homologs in protozoa, fungi, and plants. The Arabidopsis genome has nine metacaspase genes. Based on the presence or absence of an N-terminal domain, they can be divided into two types of metacaspase genes: type I (AtMC1 to 3) and type II (AtMC4 to 9). To examine the expression patterns of the Arabidopsis metacaspase gene family, we measured the levels of expression of the metacaspase genes in various tissues and during biotic stresses by quantitative reverse transcription-polymerase chain reaction. As expected, the nine AtMC genes were expressed differently among tissues and during diverse stress conditions. In addition, to address the spatial expression of AtMC genes, their expression patterns using the promoter region of AtMCs (0.85 kb to 2.55 kb) were examined by the GUS reporter system. By observing GUS activity in transgenic plants containing nine AtMCpro::GUS constructs, we found that expression of these nine AtMC genes was regulated developmentally and spatially. We also observed that AtMC::green fluorescent fusion proteins were mainly localized in the nucleus using the Arabidopsis protoplast transient assay. In summary, our data suggest that AtMCs gene family be involved in various defense responses during biotic stresses.