Eight nematode species of the order Monhysterida are described from the East Flower Garden at 72 m depth in the north–western Gulf of Mexico. The material is from sandy and rocky bottom samples influenced or beyond the influence o f a sulphide–rich brine seep. Seven species are new to science:Monhystera anoxybioticasp.n.,Gonionchus intermediussp.n.,Theristus (Theristus) coplatussp.n., Theristus (Theristus) rezaki sp.n.,Xyala oxybioticaspa.,Desmolaimoides thiobioticusgen. et sp.n. andLinhomoeus gittingsisp.n. Specimens of aLinhomoeusspecies are also described. The species is probably new to science, but the available material only includes females and juveni