Objective: To present a rare case of a mandibular bilateral simple bone cyst (SBC) with different radiological features and argue about the importance of the differential diagnosis.Case description: A 16-year-old boy was referred by his dentist to evaluate two radiolucent mandibular lesions. The diagnostic hypotheses were ameloblastoma or keratocystic odontogenic tumor to the left side and odontogenic cyst on the right side due radiologic features. In the left side, needle aspiration and biopsy, were performed. During surgical approach there was an empty space in the surgical cavity compatible with SBC. At this moment the diagnostic was made and the cavity was submitted to rigorous curettage. The right side was assessed after 4 months. To our surprise, it was found an empty cavity, as the left side. Six months later the first biopsy the panoramic radiograph showed completely bone neoformation on both sides. The patient is in radiographic follow-up for three years, without relapse.Conclusions: Bilateral SBC is a rare condition that can show different radiographic features. The diagnostic is defined at the surgery time. The radiographic features helps in diagnosis, however, should not be decisive. Surgical exploration should be done soon after radiographic diagnoses.