Five species of Axinidae (Monogenoidea: Mazocraeidae) were recovered from the gill lamellae of four of six species of needlefishes and halfbeaks examined from the Gulf of Mexico off Florida: Axine buccina n. sp. from a common halfbeak Hyporhamphus unifasciatus (Ranzani); Nudaciraxine gracilis (Linton, 1940) Price, 1962 (minimum prevalence 60%) from the Atlantic needlefish Strongylura marina (Walbaum); Nudaciraxine timucua n. sp. (36%) from the timucu Strongylura timucu (Walbaum); and Axinoides raphidoma Hargis, 1956 (29%) and Chlamydaxine truncata (Hargis, 1956) Unnithan, 1957 (29%) both from the houndfish Tylosurus crocodilus (Péron & LeSueur). The American halfbeak Hyporhamphus meeki Banford & Collette (24 specimens examined) and the redfin needlefish Strongylura notata (Poey) (94 specimens) were uninfected with axinids. The two new axinid species were figured and described. The current status of the Axinidae was explored, which suggested that an objective evaluation of its position within the Monogenoidea is needed.