Aim: The STK11 gene, also known as LKB1, encodes for a serine/threonine kinase with growth-suppressing activity, such as inhibition of cell cycle progression, cell growth retardation, apoptotic cell death, and cell polarity control. This study aimed to investigate some properties of the STK11 gene and its product, such as the homologous protein sequences in different species, the common transcription factor binding sites on their promoters, their phylogenetic relationship, their catalytic domains (S_TKc), and their expression profiles. Methods: We investigated the homology, conserved domain, promoter and expression profiles of the STK11/LKB1 genes in various species using bioinformatics approaches. Results: Our results revealed that STK11/LKB1 molecules are conserved among all organisms investigated. The kinase domain (S_TKc) of human STK11/LKB1 gene is closest to those of Pan troglodytes, Macaca mulatta and Macaca fascicularis. In contrast, the most diverse to the human S_TKc domain is that of Bos taurus. With the multiple alignment strategy, protein and domain sequences of M. fascicularis and B. Taurus are predicted to have a truncation. The comparative screening of the promoters demonstrated that STK11/LKB1 genes do not seem to have any common conserved transcription factor binding sites. Conclusion: This study demonstrated STK11 molecules in various species are well conserved throughout evolution. Comparative screening of the promoter sequences of the human STK11 and its homologues found in the NCBI database revealed that there was no any common transcription factor binding sites. Phylogenetic trees constructed using the neighbor-joining method (NJ) revealed a close evolutionary relationship of S_TKc in various species.