Background: To commpare the metallothionein (MT) immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour (KOT), to correlate MT with cellular proliferation, and to evaluate the influence of inflammation in MT. Material and Methods: Fourteen cases of KOT were submitted to imm unohistochemistry for MT and Ki-67 analysis. The lesions were grouped according to their grade of inflammation, and statistical analysis was performed. Results: MT was higher in non-syndromic KOT than in syndromic KOT (p<0.05). No statistical difference in Ki- 67 could be identified; however, an inverse correlation was observed between MT and Ki-67 in both lesions. When analysing inflammation, non-syndromic KOT showed no differences in either MT or Ki-67. Conclusions: The MT imm unophenotype of syndromic KOT was different from non-syndromic KOT. MT might not be involved in the proliferation control of both KOT. MT and Ki-67 imm unoexp ressions proved to be unaffected by inflammation in non-syndromic KOT.