A number of new collections of Opilioacaridae from Mexico, USA and Central America allowed a revision of the family in this region. Because current classification are hampered by incomplete descriptions and the use of unreliable characters, we present a brief review of characters used in distinguishing taxa within the Opilioacaridae. Characters such as the number of leaf-like setae on the palp tibiotarsus appear quite reliable, but setal numbers in the sterno-genital region show considerable intraspecific variability. Potentially valuable new characters were found in the morphology of the ovipositor. Based on the revised character set, we describe four new species from Mexico and Nicaragua, and redescribe O. texanus. A review of collection data for New World Opilioacaridae suggets the need for a re-evaluation of current ideas on habitat preference in the family.