Hamartoma is a benign tumor-like lesion composed of overgrowth of mature cells and tissues. Along with its unspecific appearance, it may occur in the oral cavity and bear resemblance to the other lesions. In this report we describes the clini-cal appearance of hamartoma as well as the diagnosis method in the case of a 37-year-old-man. The patient explained that he already has redness plaque lesion on his skin left cheek region since he was born. The lesion was sensed to grow and discomfort at the age of 22. A surgical therapy had been performed to reduce the size of lesion one year after, but the red-ness plaque still existed. Thirteen years following the operation, white lesion appeared on the inner left cheek 10 x 8.5 x 6 cm of size and extended onto lower lips within half a year. Diagnostic procedure was carried out such as biopsy, CT-scan and radiography with neuroma as an initial conclusion. New histopathological examination confirmed the diagnosis of hamartoma. It is concluded that adequate and appropriate biopsy procedure along with sufficient clinical information are needed to develop a proper diagnosis to distinguish hamartoma from other oral lesions.