Secondary bacterial infections following Viperidae snakebite envenomation in children are common. Among 75 patients admitted because of snakebites at the only pediatric hospital in Costa Rica, 16 (21.3%) had a culture-confirmed secondary bacterial infection. Morganella morganii (37.5%), Aeromonas hydrophila (31.2%), and Providencia rettgeri (18.7%) were the most common pathogens. Empiric prophylaxis is still recommended and should be based on local etiological agents and antimicrobial susceptibilities.