Caspase-13 was reported to be a member of the human caspase family of proteases (Humke, E., et al., J. Biol. Chem. 273, 15702-15707, 1998). By contrast, a recent study (Lin, X., et al., J. Biol. Chem. 275, 39920-39926, 2000) could not confirm caspase-13 expression in human tissues. When we searched the GenBank database we found several expressed sequence tags (ESTs) from bos taurus completely matching the published caspase-13 sequence. Reverse transcription polymerase chain reaction (RT-PCR) analysis revealed that bovine but not human peripheral blood mononuclear cells express caspase-13. From these cells we cloned two bovine caspase-13 splice variants and found that the sequence of the larger variant was identical to the mRNA published by Humke et al. Our findings strongly suggest that the previously published caspase-13 sequence is not of human origin but represents a bovine gene.