Radicular cysts are commonest pathology of jaw bones, which is odontogenic in origin. Due to delayed diagnosis, some lesions can reach significantly large dimensions and may extend to adjacent anatomic structures. Here, we are presenting a case of a maxillary radicular cyst large enough to involve maxillary sinus. This patient also had multiple periapical pathologies related to carious teeth or remnants of teeth. All the lesions were managed successfully, without recurrence. Differential diagnosis of such a common lesion is very important in view of appropriate management and good clinical response.