BACKGROUND: Biotic processes, such as predation and parasitism events, are crucial for answering questions in ecology and evolution. Here, we report predation and ectoparasitism events of invertebrates upon tadpoles in aquatic habitats of southern Brazil. FINDINGS: Four lentic water bodies were sampled twice a month (December 2012 to March 2013). Those water bodies were located in the Diamante do Norte County, State of Paraná, southern Brazil. The tadpoles, Dendropsophus aff. minutus, Hypsiboas raniceps, Scinax fuscovarius, Physalaemus cuvieri and Elachistocleis bicolor were observed being predated by six different invertebrate predators. However, Leptodactylus fuscus and Pseudis sp. were also recorded on the same water bodies and were not observed being preyed or parasitized. The most abundant predator in our sampling areas was the diving beetle larvae. We observed a static and escape behavior of tadpoles when in close proximity to predators and constant movements in E. bicolor tadpoles, which can be advantageous for invertebrate predators. Parasitism events included D. aff. minutus, S. fuscovarius,andE. bicolor tadpoles that were infected by a single leech. The ectoparasites anchor the posterior sucker on the host tadpole during the blood feeding. CONCLUSIONS: Even isolated reports of ecological interactions are important for understanding ecological communities and the impacts of parasites and predators on tadpoles' populations. Additionally, these interactions can help to understand the ecology behavior of the organisms.