Two new species of the genus Isotomiella Bagnall, 1939 are described and illustrated, the first: I. macedoi sp. n., based on males and females, from the "Parque Nacional da Serra dos Órgãos" (Teresópolis municipality, State of Rio de Janeiro) differs from the other by tibiotarsus III thickened and blunt and two antero-lateral chaetae of labrum strongly thickened. The second species I. uai sp. n. from "Serra da Gandarela", (Caetémunicipality, State of Minas Gerais) differs from the other by presence of short sensilla on antennal IV and tergites, two anterolabral chaetae thickened and falcate mucro. [ABSTRACT FROM AUTHOR]