An ostracode fauna from the Macoupin cyclothem, McLeansboro group(sic), is described. The fauna consists of 13 previously described species and 13 new species. The following genera are represented: Beyrichiana, Kirkbya, Amphissites, Discoidella, Monoceratina, Bairdia, Macrocypris, Bairdianella, Cytherella, Bythocypris, Cavellina, Basslerella, and Cypridellina.