Objective: To evaluate the effectiveness of the modified endoscopic Lothrop (MEL) procedure for the management of failed osteoplastic flap (OPF) with obliteration of the frontal sinuses. Setting: Adelaide University Academic Hospital Complex. Study Type: Prospective case study of 16 patients presenting with symptoms after OPF with obliteration of the frontal sinuses. Materials and Methods: Sixteen patients presented with symptoms of frontal sinus pain after having previously undergone OPF and fat obliteration of the frontal sinuses. All patients underwent computed tomography scanning; 13 underwent magnetic resonance imaging scanning, and 6 underwent a bone scan with technetium to exclude frontal osteitis. All patients underwent exploration of the frontal sinuses by way of the MEL procedure. Results: Fifteen patients were found to have a frontal sinus mucocele, whereas one patient had no mucocele with only new bone and fibrous tissue found at the MEL procedure. Twelve of the 16 patients with mucoceles had resolution of their frontal headaches, with 15 having a patent and healthy communication between the mucocele and the nasal cavity. The one patient without a mucocele continues to have frontal pain. One patient underwent a successful MEL procedure but had persistent symptoms until a supraorbital ethmoid mucocele was removed at a revision procedure. Two other patients continued to have frontal headaches and pain despite a healthy ostium into the frontal sinus mucocele. Conclusions: MEL is a viable alternative to revision OPF for symptomatic patients who are shown to have a mucocele of the frontal sinuses.