During a study on parasites of fish from cenotes (= sinkholes) in the Yucatan Peninsula, the following cestodes and acanthocephalans were found in 581 freshwater fish of 15 species: the cestodes Bothriocephalus acheilognathi Yamaguti, 1934, Bothriocephalus sp. (Bothriocephalidae), Nomimascolex sp. (Monticellidae), Proteocephalidea gen. sp. larv., Dendrouterina pa-pillifera (Fuhrmann, 1908) larv. and D. pilherodiae Mahon, 1956 larv. (Dilepididae), and the acanthocephalans Octospinifer-oides chandleri Bullock, 1957, Neoechinorhynchus golvani Salgado-Maldonado, 1978 (Neoechinorhynchidae), Polymorphus (syn. Arhythmorhynchus) brevis (Van Cleave, 1916) larv. (Polymorphidae), and an echinorhynchid larva. With the exception of B. acheilognathi, all tapeworms are found in Mexico for the first time; second-stage larvae of D. papillifera and D. pilherodiae from fish are reported for the first time.