New data on Iranian spiders is provided based on 92 specimens collected from the interiors or surroundings of 27 caves. These specimens belong to 17 species in nine families, of which five species are described as new to science: Tegenaria pallens Zamani & Marusik, sp. n. (♂♀; Gakal Cave, Kohgiluyeh & Boyer-Ahmad Province) (Agelenidae); Dysdera elamana Zamani & Marusik, sp. n. (♂; Barreh Zard Cave, Ilam Province); and Harpactea zagros Zamani & Marusik, sp. n. (♂; Raad-e Gharbi Cave, Ilam Province) (both Dysderidae); Troglohyphantes megagynus Zamani & Marusik, sp. n. (♀; Kabootarlan Cave, Ilam Province) (Linyphiidae); and Mesiotelus iranicus Zamani & Marusik, sp. n. (♀; Mir Melas Cave, Lorestan Province) (Liocranidae). Additionally, two genera, Scotargus Simon, 1913 and Odontodrassus Jézéquel, 1965, and three species, Odontodrassus mundulus (O. Pickard-Cambridge, 1872) and Synaphosus syntheticus (Chamberlin, 1924) (both Gnaphosidae), and Scotargus pilosus Simon, 1913 (Linyphiidae), are recorded in Iran for the first time. The newly described and recorded species are accompanied by illustrations.