Arginase is an enzyme that catalyzes the amino acid arginine to produce ornithine and urea. It is the sixth and final enzyme in the urea cycle. There are two types of arginase: Arginase I and Arginase II. Arginase I is primarily found in the liver while Arginase II is primarily found in the mitochondrial kidney. Arginase I functions for urea synthesis and Arginase II functions for ornithine synthesis. 15 different species were aligned and compared based on the protein sequences of their arginase enzymes. It was hypothesized that the arginase enzyme amino acid sequences and metabolic functions among more complex eukaryotic species would display a high degree of similarity among many other diverse eukaryotic organisms. The results from the phylogenetic tree display high bootstrap values between species previously known to be closely genetically related such as between primates, fish, and avian species. The data obtained from the weblogo alignment also suggest a high degree of arginase amino acid sequence similarity between the various species. The data obtained from both of these programs and the research conducted on the structure and metabolic function of both isoforms of arginase among ammonotelic, uricotelic, and ureotelic organisms is consistent with our hypothesis that similar arginase amino acid sequences can be seen among many diverse species, supporting a degree of genetic relationship and possible common ancestry.