A description of the coccidium Isospora hemidactyli from the house gecko Hemidactylus mabouia, a very common at dwellings in Rio de Janeiro Metropolitan Region, was made in this study. Histograms and linear regression were made for this species and determined the homogeneity of these oocysts despite of large range. Besides it, polysporocystid oocysts also were recovered from feces of the H. mabouia house gecko and they were similar to those described previously as the genus Adelina. This species should be parasitizing an invertebrate ingested by house gecko, and for that reason, is a pseudoparasite. Oocysts of I. hemidactyli were subspherical to ellipsoidal, 24.4 x 22.3 microm, with single-layered wall and one polar granule. Sporocysts were subspherical to ellipsoidal, 11.8 x 9.8 microm with Stieda and substieda bodies, residuum and sporozoites with refractile body. Oocysts of the pseudoparasite Adelina sp. were ellipsoidal, 36.3 x 30.9 microm, with bi-layered wall and without micropyle, residuum and polar granule. Eight to 15 sporocysts were presents and were subspherical to broadly ellipsoidal, 12.4 x 11.2 microm. Stieda and substieda bodies were absent. Sporozoites present refractile bodies at both ends.