We reviewed the case histories of five patients with orbital complications caused by acute sinusitis to characterize the effective treatment of this disease. We treated five patients with orbital complications caused by acute sinusitis in Kanazawa University Hospital between 2002 and 2004. Patient 1 presented with postseptal orbital cellulitis and was successfully treated with intravenous antibiotics. The remaining four patients presented with orbital subperiosteal abscess (SPA) and underwent the surgical treatment (patients 2-5). Of the four patients with SPA, two presented with medial SPA (patients 2 and 3) and the remaining two patients presented with superior SPA (patients 4 and 5). Both patients with medial SPA were children. Patient 2 successfully underwent transnasal endoscopic drainage. Patient 3 initially underwent transnasal endoscopic drainage. However, the patient had persistent periorbital edema and erythema, and a repeat CT on postoperative day 3 showed the anterior extension of the SPA. A second surgical drainage via an external approach was required in this patient. Both patients with superior SPA were adults. Patient 4 underwent transnasal endoscopic drainage at another hospital. However, the patient had persistent periorbital edema and erythema and was referred to our hospital. This patient required combined drainage via both endoscopic and external approaches. Patient 5 initially underwent combined drainage via both endoscopic and external approaches. In summary, medial SPA can be drained via an endoscopic approach in many cases. However, some cases may require drainage via an external approach. Superior SPA may be successfully drained via an endoscopic approach; however, the risk of incomplete drainage appears to be high.