The peripheral lymphocyte subsets were analyzed in 37 patients with VKH and 32 normal controls by indirect fluorescein assay, using monoclonal antibodies. The percentages of OKT3+, OKT4+, and OKT8+ T-cells in active patients were found to differ insignificantly from those in quiescent patients, as were those in patients of the VK type from those in patients of the Harada type (P > 0.05), whereas the percentage of OKT4+ was significantly higher, that of OKT8+ was lower, and the OKT4/OKT8 ratio was higher in the recurrent patients than in the controls (P < 0.01). There was statistical difference in the ratio of OKT4/OKT8 between the recurrent and the non-recurrent patients (P < 0.01), while the ratio differed insignificantly between the two types of recurrent patients. The results suggested that the recurrence of VKH could be related with imbalance between the T-cell subsets.