A cross-sectional survey was undertaken to determine the magnitude, manifestations, and practices related to Onchocerciasis on 1337 students of six junior secondary schools of Kafa Zone in January 1993. Information on symptoms of the disease and the frequency of common practices that would bring the subjects to the breeding sites was collected by interview, while physical measurements and clinical examination was used to collect data on visual acuity, nutritional status and objective manifestations of the disease. Skin snip from both gluteal areas was examined to determine the microfilarial rate and density of infection, while nutritional status using Body Mass Index for Age (BMI-for Age), and visual impairment following the standard procedures was categorized. The majority, 1179 (88.2%) of the subjects, were aged 15 years and less of which males constituted 54.5% (728). The overall microfilarial carrier rate was 15.6% (95% CI = 13.7-17.6%) while the density of infection was 1.4 mf/mg skin snip. The prevalence and density of infection varied significantly among the twelve aggregates of villages identified based on the similarity of the ecological feature and contiguity of home address of the students. Males had significantly higher rate and density of infection but the difference by age was not significant. The prevalence of infection was significantly higher among the students who had reported frequent bathing, swimming, fishing and collecting firewood at/or near the rivers identified as the probable breeding sites of the vector, while there was no statistically significant association between infection and washing clothes, fetching water or crossing over the rivers. Groin lymph nodes enlargement, photophobia and itching were the leading symptoms complained by the infected subjects. However, only itching and the objective features related to the cutaneous Onchocerciasis were significantly associated to the infection. Visual acuity didn't differ among positive and negative subjects. Nutritional status was significantly associated with Onchocercal infection. Based on these findings recommendations are given on the areas of intervention and further study.