INTRODUCTION: Platelet activation plays a key part in the process of atherosclerosis. The risk of atherosclerosis increased in familial Mediterranean fever (FMF). Mean platelet volume (MPV), platelet distribution width (PDW) and platelet counts are important in platelet activation. The aim of present study was to evaluate the relationship between the MPV, PDW, PLT counts and mutation types of FMF in children in attack free period. MATERIALS and METHODS: PLT counts, MPV, PDW, age, sex and mutation types of patients were recorded retrospectively from medical records of patients. Three hundred sixty-eight children with FMF in attack-free period and 379 healthy children were included in the study. RESULTS: MPV of the patients were lower than those of control (p<0.001). However PDW counts of the patients were higher than those of control groups (p<0.001). The PLT counts were not different between patients and control subjects (p<0.05). Of 368 patients; homozygous, heterozygous, and compound mutations were seen, respectively, in 51, 267, and 51 patients. The MPV of patients with homozygous (p=0.029) and heterozygous(p=0.041) mutations were found higher than that of patients with compound mutations. There was no difference between heterozygous and homozygous mutation in terms of MPV (p<0.05). In addition, there was no difference between heterozygous, homozygous and compound mutations in terms of PDW and PLT counts (p<0.05). The most common mutations were M694V (n=131), E148Q (n=82), M680I, (n=37), and V726A (n=32). There wasn’t seen significant difference among these mutations in terms of MPV, PDW and PLT counts (p < 0.05). CONCLUSIONS: Although, atherosclerosis risk is increased in high MPV levels, we couldn’t find this relationship in current study. It may be due to all the patients were under colchicine treatment. On the other hand PDW levels were found higher in patients than control group. To verify this relationship between PDW and MPV values, further investigations are needed.