Early detection of oral potentially malignant epithelial lesions (PMELs) is aimed at improving survival rates as carcinogenesis is a multistep process and prevention is possible if these lesions are detected at an early and reversible stage of the disease. A prospective clinical study aimed at determining the prevalence of bilateral 'mirror-image' oral PMELs was carried out. Sample consisted of 32 (53.3%) Indians, 23 (38.3%) Chinese, 4 (6.7%) Malays and one (1.7%) Nepalese. All had histopathological confirmation of their primary existing PMEL as inclusion criteria. A total of 70 primary lesions were detected. The most common PMEL found was oral lichen planus. Of these, 28 (46.7%) patients exhibited bilateral 'mirror-image' lesions (n = 42) either synchronously (n = 32/42) or metachronously (n = 10/42). The remaining 32 (53.3%) patients had normal-looking contralateral mucosa. Present findings suggest that patients presenting with oral PMELs are at greater risk of developing a second lesion, most probably in the contralateral 'mirror-image' site.