Objective:To study the antimicrobial activity of diacerein on common pathogens of the ocular surface in vitro.Methods:Pathogens were collected from patients with ocular surface infections in Henan Eye Hospital, including Gram-positive cocci and bacilli, Gram-negative bacilli, filamentous fungi, and Candida.The antimicrobial activity of diacerein was determined by the K-B agar diffusion method, and its minimum inhibitory concentration (MIC) was determined by the micro-liquid method.Levofloxacin and voriconazole were used as the control of antibacterial and antifungal drug, respectirely.Results:Diacerein showed antibacterial activity against 42 strains of Gram-positive cocci and 10 strains of Gram-positive bacilli, its inhibition zone diameters for Staphylococcus epidermidis, S.aureus, S.intermedius and Gram-positive Corynebacterium were not significantly different from those of levofloxacin (all at P>0.05). Its MIC range of diacetate against Staphylococcus epidermidis, S. aureus, S. intermedius and other Staphylococci was 1-32 μg/ml, and its respective MIC 90 was 16, 8, 16, and 32 μg/ml.Diacerein had no bacteriostatic effect on 23 strains of Gram-negative bacilli, 10 strains of filamentous fungi and 3 strains of candida. Conclusions:Diacerein has antibacterial effects against Gram-positive Staphylococcus and Corynebacterium isolated from the ocular surface, but shows no antimicrobial activity against Gram-negative bacilli and fungi.Diacerein offers a new drug option and method for the treatment of bacterial keratitis.