Abstract Marine sediments were deposited in western Libya during most of Paleozoic time. The resulting rock section consists of a thick sequence of detrita rocks, largely dark-gray shales and sandstones, ranging in age from Cambrian to Permian. A high proportion of the fine-grained detrital rocks from the Cambrian through Carboniferous Systems contain spores, pollen, hystrichospheres, and/or chitinozoans. A variety of hystrichospheres occurs in most of the marine Paleozoic rocks. Although some hystrichospheres are stratigraphically significant throughout the Paleozoic, they are particularly important in the Cambro-Ordovician section, where pollen and spores are absent. Chitinozoans are encountered most commonly in Silurian and Devonian strata. The earliest occurrence in Libya of spores of vascular plants is in rocks of early Silurian age. The Silurian palynomorph assemblage is dominated by smooth trilete spores. Spores constitute less than 10 percent of the total palynological assemblage in the lower part of the Silurian, but generally comprise a larger proportion of the total assemblage in upper Silurian rocks; the remainder of the population is composed primarily of hystrichospheres. An abundant and diverse assemblage of palynomorphs is encountered in Devonian rocks. It is characterized by trilete spores with various kinds of sculpturing and ornamentation. Smooth, spinose, and reticulate spores are common, as are zonate and monosaccate spores. Trilete spores with radiating ridges are also found. The Carboniferous assemblage is distinguished by spores with an equatorial flange, triangular zonate spores with distal spines, trilete reticulate spores, and monosaccate forms. The frequent occurrence and excellent preservation of these palynological assemblages, often when other fossils are rare or absent, permits zonation and correlation of Paleozoic strata in western Libya. These rocks also provide a source of material that can contribute to an overall understanding of the stratigraphie ranges, evolution, and phylogeny of spores, pollen, and certain groups of microplankton during Paleozoic time.