|Abstract||In a countrywide study of the geographical distribution patterns of chicken lice in Nigeria, 3 species, Menacanthus pallidulus (Neumann 1912), Goniodes dissimilis Denny, 1842, and Menopon gallinae (Linnaeus, 1758), were completely restricted to within areas with a long humid season (6-12 humid mo per yr). In constrast, 4 species, Cuclotogaster occidentalis Tendeiro, 1954, Menacanthus cornutus (Schommer, 1913), Amyrsidea powelli (Bedford, 1920), and Goniodes gigas (Taschenberg, 1879), thrived only in areas where the humid season was of a short duration (< or = 5 mo). The last 3 named species extended also into the fringes of areas with a long humid season (6-8 humid mo) at significantly reduced numbers. They were entirely absent in areas with a particularly protracted humid season (9-12 humid mo). Three other species. Numidilipeurus tropicalis (Peters, 1931), Goniocotes gallinae (DeGeer, 1778), and Lipeurus caponis (Linnaeus, 1758), were just as abundant in areas of a long humid season as they were in areas with a short humid season. It was concluded that there was an association between duration of the humid season and the geographical distribution patterns of certain species of chicken lice in Nigeria. The duration of the humid season might thus provide a means of predicting the potential occurrence of some species of chicken lice in a particular area.