Tickborne relapsing fever (TBRF) is a bacterial infection caused by certain species of Borrelia spirochetes and transmitted through the bite of Ornithodoros ticks. Clinical illness is characterized by relapsing fever, myalgias, and malaise. On May 10, 2011, CDC and the Colorado Department of Public Health and Environment were notified of two patients with TBRF: a young woman and her newborn child. This report summarizes the clinical course of these patients and emphasizes the importance of considering a diagnosis of TBRF among patients with compatible clinical symptoms and residence or travel in a TBRF-endemic area. Pregnant women and neonates are at increased risk for TBRF-associated complications and require prompt diagnosis and treatment for optimal clinical outcomes. Public health follow-up of reported TBRF cases should include a search for persons sharing an exposure with the patient and environmental investigation with remediation measures to prevent additional infections.