In this study, lymphocytes subsets including blood CD3, CD4, CD8, CD16, CD19, and CD56 values were analyzed in children with febrile convulsion (FC) to determine whether there was the association of lymphocytes subsets in the pathogenesis of FC. The study includes 48 children with FC, and 55 healthy age matched control subjects, followed in Yuzuncu Yil University, Faculty of Medicine, Department of Pediatrics between October 2003 and June 2004. Blood CD3, CD4, CD8, CD16, CD19, and CD56 values were examined in the study and control groups. The analyses were performed in the Hematology Laboratory, Yiizuncu Yil University Faculty of Medicine, with flow cytometer device (Coulter Epics XL2, Flow Cytometer). A total of 48 children [17 girls (35.5%) and 31 boys (64.5%)], aged 6 months to 60 months (mean 22.20 +/- 13.75 months) with FC and 55 healthy children [28 girls (51%) and 27 boys (49%)], aged 6 months to 60 months (mean 28.87 +/- 17.04 months) were included in the study. When compared with the control group, the study found significantly decreased blood CD3 and CD4 values in the study group (p < .05). However, there was not significant difference in CD8, CD 16, CD19, and CD56 values between the control and study groups (p > .05). When comparing the children with and without positive family history for FC, the study did not find any difference for all CD values between the groups (p > .05). Similarly, there was not significant difference in CD values between the children with simple and complex FC (p > .05). The findings suggested that decreased blood CD3 and CD4 values might be responsible for the infections connected with FC or that they might be related to the pathogenesis of FC in some children.