Aim: The aim of this study was to evaluate clinically and radiographically the effect of LIPUS stimulation on bone healing of large cystic defects.Subjects, Material & Methods: The present study was performed on sixteen adult patients of both sexes, of middle age, ranged from 20-45 years, with mean age of 28 years, suffering from large intrabony cystic lesions, with diameter (≥2cm), in the maxilla, selected from the outpatient clinic of Oral & Maxillofacial Surgery Department, Faculty of Oral and Dental Medicine, Cairo University. Patients were randomly divided into two equal groups (eight patients per each), the patients of both groups were operated on to enucleate the bony cystic lesions surgically. Patients of the study group only (Group I) were subjected extraorally to low intensity pulsed ultrasound after surgery to the area of enucleated lesion. LIPUS was applied 3times per week for 4 weeks starting from the day of surgery. Time of application was 7 minutes at dose 1 W/cm2. Cone beam computed tomography radiographs were performed to measure the bone density within the left bony cavity in both groups at time intervals of one day and six months after surgical procedure.Results: Results revealed that LIPUS group (Group I) showed minute increase in bone density values compared to control group (Group II) however that minute increase is not statistically significant.Conclusion: LIPUS therapy had no significant effect on maxillary bone healing after enucleation of cystic lesion regarding bone density measured by cone beam computed tomography. Also, cone beam computed tomography is recommended in tracing bone density changes, because of the 3D measurements which are accurate and precise radiographic technicalities.