Brown spiders (Loxosceles spp.) are venomous arachnids, successfully adapted to urban habitats in Brazil. Loxoscelism became a serious public health problem in Paraná State, especially at the capital Curitiba, where the most abundant species is Loxosceles intermedia. Hemidactylus mabouia (Gekkonidae) lizards are synanthropic predators of arthropods. In this paper, we describe the predatory behavior of the Tropical House Gecko H. mabouia on L. intermedia under laboratory conditions. Twelve geckos were observed, and all of them fed on brown spiders (n=123 observations). The attack consisted of a fast run followed by one bite on the spider’s abdomen or legs. The geckos did not attack L. intermedia anterior body parts, probably due to the fangs present in this region. Two Hemidactylus individuals were killed by L. intermedia bites: during a predatory encounter, and by an induced bite on a restrained lizard. The observations summarized in this paper show that H. mabouia could be used in the biological control of Loxosceles populations in human dwellings. However, additional field studies are necessary to quantify the impact of H. mabouia predation on urban populations of L. intermedia and other species of the same genus.