The conjunctival flora of 499 patients was studied the day before cataract extraction, no antibiotics or chemotherapeutical agents had been used before admission. Staphylococcus albus was by far the most common micro-organism (95.4%), followed by corynebacteria (44%), Staphylococcus aureus (14.9%), gram-negative bacilli (7.8%) and pneumo-streptococci (4.4%). Corynebacteria was isolated more frequently in the presence of S. albus, while S. aureus and gram-negative bacilli were found more frequently in the absence of S. albus. No relationship could be demonstrated between the occurrence of pneumo-streptococci and S. albus. The flora of the nose and skin of the face were studied and compared with the conjunctival flora, and a similarity could be observed. Furthermore, strains of S. aureus isolated at the same time from the two or three regions, in most cases, showed the same bacterio-phage type complex. The conjunctival flora was further correlated with sex, age, season, and number of polymorphonuclear neutrophils recovered from the conjunctival fluid. The incidence of corynebacteria and gram-negative bacilli was found to be higher in males, while corynebacteria was the only organism to show seasonal variation, i.e. was isolated more frequently in the second and third quarters of the year. No correlation could be found between age or number of neutrophils.