Purpose: We aimed at evaluating cases ofacute l;ucterial conjunctivitis both clinically and bacteriologcically to determine the most prevalent causative bacteria and their antibiotic senslliities as an epidemiological study in Benha. Methods : 500 patients of different age groups clinically diagnosed to have acute bacterial conjunctivitis were selected and studied c1inicobacteriologically to determine the causative bacteria. 60 persons not suffering from any signs or symptoms were taken as control. Results : of 500 cases. 348 (76.8%) gave positive growths. Staphylococcus aureus was isolated in 30.6% ofcases followed by H. influenzae 14%, Neisseria catarrhal is 12%, Staph. albus II %, Streptococci 9.4%, Diphtheroids 6%, Streptococcus pneumoniae 4.6% and others. Conclusion : Staph. au reus was the commonest organism isolated in different age groups and in different seasons in an incidence of 30.6% ofcases, 23.2% ofthe selected cases gave no growth. The cases revealed negative growth must be examined thoroughly to exclude chlamvdial and viral infections. Tobramycin, Gentamicin and Chloramphenicol were the most effective antibiotics in the majority ofcases.