Background Sphenoid mucoceles (SMCs) are unusual lesions, with about 130 cases reported in the literature. Although benign, they may involve the orbit and cause acute restrictive ophthalmoplegia, proptosis, and reduced visual acuity. Methods and results We present three cases (1 male, 2 females, aged 35, 36, and 46 years) of orbital involvement with acute decreased visual acuity by SMC. The lesions were promptly excised via a transnasal approach to decompress the optic nerve. After the decompression, the patients recovered completely. Conclusion We believe that immediate surgical drainage of the SMC and prolonged antibiotic therapy are necessary and resulted in recovery of visual acuity. Prompt microsurgical transsphenoidal decompression is simple, effective, safe, and is necessary for avoiding persistent visual loss. Antibiotic therapy alone usually results in a poor outcome. We discuss the etiology, clinical manifestations, and management of this rare condition in the light of 130 other cases in the literature. (C) 2001 by Elsevier Science Inc.