Objectives: Maxillary cancer is notorious for its poor prognosis because it is usually detected lately and the majority of patients have advanced disease. Especially when the cancer extended to infratemporal fossa or pterygopalatine fossa it is very difficult to remove all the involved structure by conventional maxillectomy. In these cases we have used radical maxillectomy through lateral approach. We tried to figure out the clinical significance of this procedure. Material and Methods: This study retrospectively analyzed 23 patients with squamous cell carcinoma of the maxillary sinus who underwent surgical treatment for cure. Among them 17 patients(group A) were treated with initial surgery and 6 patients(group B) underwent salvage surgery after radiotherpy. Radical maxillectomy was performed in 12 patients and conventional total maxillectomy in 11 patients. Results: In group A, 3 out of 9 total maxillectomy case and none of 8 radical maxillectomy case were recurred. In group B one patient died of postoperative complication and among the other 5 patients only one out of 3 radical maxillectomy was salvaged and 2 total maxillectomy cases were died of intercurrent disease. Conclusion: Wide surgical dissection of pterygopalatine fossa and infratemporal fossa may improve the survival rate in patients with posterior wall invasion of maxillary sinus.