Mostly bFGF was correlated with ASL-O (among boys r = 0.45, patients with oligoarthritis r = 0.49, moderate disease activity according to JADAS-27 r = 0.58, MTX treatment r = 0.38, dosage of MTX, 12.5–15 mg/m2/week r = 0.50 p < 0.05), CIC (among patients with polyarthritis r = 0.37, low disease activity according to JADAS-27 r = 0.34, dosage of MTX, less than 10 mg/m2/week r = 0.96 p < 0.05), and ESR (among girls r = 0.37, patients with polyarthritis r = 0.38, p < 0.05). This evidence concerns the gene FGF2 and polyarticular arthritis.