There are two types of tRNA 3' processing endoribonucleases (tRNase Z): a short form (tRNase ZS) and a long form (tRNase ZL). Although the human genome contains both genes, little is known about the physiological role of tRNase ZS. We found that the human tRNase ZS gene expression appears to be post-transcriptionally regulated. Additionally, analyses for cis-regulatory elements for the tRNase ZS gene transcription suggested that transcription factors that bind to five different sites on the promoter work together to potentiate the transcription initiation. Furthermore, we found that tRNase ZS is predominantly present in the cytosol and hardly in the nucleus.