The Pirai River may refer to: the Piraí River (Bolivia), a river in eastern Bolivia the Piraí River (Paraná), a river of Paraná state in southern Brazil the Piraí River (Rio de Janeiro), a river of Rio de Janeiro state in southeastern Brazil the Piraí River (Santa Catarina), a river of Santa Catarina state in southeastern Brazil the Pirai River (India), a river of India