Background: Blood neutrophil to lymphocyte ratio (NLR) and mean platelet volume (MPV) both have been used as a simple marker of inflammation in many disorders. Here, we aimed to investigate the relationship between NLR, MPV, and familial Mediterranean fever (FMF). Materials and Methods: In this retrospective study, the files of FMF patients in pediatric rheumatology outpatient clinic were reviewed. There were 160 participants (68.4%) in the FMF patient group and 74 participants (31.6%) in the control group. Ninety of patients were in attack-free period, and 70 were in attack period. Results: The highest values of NLR were found in the patients at attack period. Patients in attack-free period and the participants in control group had similar levels of NLR (1.71 ± 0.83 and 1.91 ± 1.86 respectively) (P = 0.457), and they had lower ratios than the patients did at attack period (4.10 ± 3.11) (P < 0.001 for both). There was no significant difference between MPV values of attack patients (8.35 ± 4.91) and attack-free patients (8.43 ± 1.15) (P = 0.074). MPV values of attack patients and attack-free patients were significantly higher than control group (7.99 ± 0.81) (P < 0.001 for both). Conclusion: NLR ratio may indicate FMF attack period. Since there was no significant difference between attack-free patients and control groups, NLR ratio cannot be used as a subclinical inflammation marker. However, NLR could be a useful predictor of inflammation in FMF patients. On the other hand, since our attack and attack-free patients have similar MPV values and both had greater MPV values than control group, we suggest that MPV may be used to show subclinical inflammation.