Abstract: OBJECTIVE To investigate the effect of tacrolimus on immunological rejection after fungal keratitis in patients with fungal keratitis, so as to provide references for clinical treatment of fungal keratitis. METHODS A total of 56 cases (57 eyes) of patients with fungal keratitis in the treatment of penetrating keratoplasty from Mar. 2010 to Feb. 2017 were retrospectively analyzed. According to the different treatment methods after treatment, the patients were divided into control group of 23 cases (23 eyes) and experimental group of 33 cases (34 eyes), and all patients were given conventional anti-fungal anti-inflammatory treatment before the operation, the main drugs were: fluconazole eye drops, levofloxacin eye drops fluid and ofloxacin ointment. The total course of treatment before and after surgery was less than 2 weeks, and we paid attention to observe the patient's vital signs. The tissue and mycelial moss of necrosis on the surface of the lesion's cornea were removed by operation, and then the patients were treated with antifungal agents after the operation. The patients in control group were treated with cyclosporine A eye drops, and in experimental group were treated with tacrolimus fluid to the last follow-up, and patients still continued to use low concentrations of glucocorticoid for treatment. The effect of postoperative treatment, immune rejection, other complications and other data were observed at 1 month after the operation. RESULTS Totally 43 strains of fungi were cultured and isolated in the two groups of patients, which were mainly Fusarium, Aspergillus, Alternaria, and Candida. Among which, Fusarium were 24 strains, accounting for 55.81%, and Aspergillus were 14 strains, accounting for 32.56%. After a month of treatment, there was no significant difference in the effective rate between the two groups. In experimental group, the number of cases of immunological rejection was 5 cases, which was lower than 10 cases in control group (P<0.05). The best corrected visual acuity between the two groups had no significant difference. During the hospital stay and follow-up period, the two groups of patients did not occur the corresponding complications. CONCLUSION Tacrolimus can effectively inhibit the postoperative immune rejection, the effect is significant and the safety was high.