Symptomic and asymptomic infections of Demodex spp. in eye lashes of patients of different age groups. Demodex folliculorum and Demodex brevis were looked for on eyelashes sampled from 481 people, aged 3 through 96. The persons studied were divided into 9 age groups. Magnitude of the infection symptoms was assessed based on macroscopic changes of eye-lid edges and on interviews with patients. An increase of the prevalence of infection and intensification of the symptoms were observed to coincide with the age increase of the persons studied. No significant differences were demonstrated between the infection frequencies of women and men. Symptoms of ocular demodecosis were more frequent only in women of group III (aged 21-30) and group V (41-50) (p<0.05).