Unilocular bone cysts are the most common entities affecting the maxillofacial region. The mechanism of proliferation and expansion remains unclear. Metalloproteinases (MMPs) are associated to diverse pathological conditions. The aim of the present study was to correlate the radiographic aspect (area) and the presence of MMP-2 and MMP-9 in dentigerous cysts, radicular cysts and keratocystic odontogenic tumors. The radiographic area of each lesion was calculated using the mathematical formula of the ellipse area. All specimens were subjected to immunohistochemical analysis for these enzymes. The average radiographic area was 284.17 mm2, 235.81 mm2 and 381.81 mm2, respectively. Statistical analyses revealed no association between the immunoreactivity of MMPs and radiographic area of the lesions in all pathologies studied, except for MMP-2 and radicular cysts, for which smaller lesions had increased immunostaining for this enzyme. The results demonstrate that quantities of MMP-2 and MMP-9 are especially involved with dentigerous and radicular cysts in expansion, whereas these enzymes seem to be related to the biological behavior of keratocystic odontogenic tumors, indicating invasion and cell proliferation. Moreover, there is an inverse association between MMP-2 and MMP-9 in keratocystic odontogenic tumors (p=0.03; rs=-0.660), indicating activity in different regions.