In the fourth of a series of papers dealing with <i>Laboulbeniales</i> in Poland descriptions of two new species: <i>Autophagomyces falcatus</i> sp.n. on <i>Cryptophagus pilosus</i> and <i>Euphoriomyces octotemni</i> sp.n. on <i>Octotemnus globriculus</i> are given The remaining seven species mentioned in the paper are new for Poland and one of them (Rhachomyces speluncalis) was observed for the first time in Europe.