A 5-year-old Massachusetts resident developed hard tick-borne relapsing fever caused by Borrelia miyamotoi. A partially engorged Ixodes scapularis tick was removed from her scalp and identified as infected with B. miyamotoi using polymerase chain reaction. Two weeks later, she developed an illness compatible with B. miyamotoi infection that included fatigue and recurrent fever. The diagnosis was confirmed by B. miyamotoi seroconversion.