Demodex is easily found from eyelashes and suggested as the one of the causes of some eye diseases. This study was to investigate the occurence rate, and classification of Demodex from eyelashes, and its relationship with blepharitis. The data of this study were compiled from 27 blepharitis patients and 173 patients without blepharitis (control group) who had visited St. Paul's Hospital from October 1981 to December 1981. Three eyelashes from each eyelid-total 12 lashes from a patient-were extracted under the slit lamp, located on a slide glass and fixed with polyvinyl lactophenol mounting medium. (countinued..)