BACKGROUND: Butyrylcholinesterase is an enzyme that may serve as a marker of metabolic syndrome. We (a) measured its level in persons with diabetes mellitus, (b) constructed a family tree of the enzyme using nucleotide sequences downloaded from NCBI. Butyrylcholinesterase was estimated colorimetrically using a commercially available kit (Randox Lab, UK). Phylogenetic trees were constructed by distance method (Fitch and Margoliash method) and by maximum parsimony method. RESULTS: There was a negative correlation between serum total cholesterol and butyrylcholinesterase (-0.407; p < 0.05) and between serum LDL cholesterol and butyrylcholinesterase (-0.435; p < 0.05). There was no statistically significant correlation among the other biochemical parameters. In the evolutionary tree construction both methods gave similar trees, except for an inversion in the position of Sus scrofa (M62778) and Oryctolagus cuniculus (M62779) between Fitch and Margoliash, and maximum parsimony methods. CONCLUSION: The level of butyrylcholinesterase enzyme was inversely related to serum cholesterol; dendrogram showed that the structures from evolutionarily close species were placed near each other.