Tithonia diversifolia is an invasive species, widely distributed in Brazil and with important ecophysiological aspects to be addressed, such as its allelopathic action or its therapeutic use. The present study aimed to compare the allelopathic actions of hydroalcoholic extracts of leaves of Tithonia diversifolia from three localities in the State of Espírito Santo/Brazil. For this purpose, two species were used as test organisms, Lactuca sativa and Solanum lycopersicum, which had their seeds germinated in Petri dishes lined with filter paper, in contact with different concentrations (0.5, 1.0 and 5.0 mg.mL-1) of the leaf extracts of Tithonia diversifolia. For the negative control distilled water was used. In the experiments several parameters were evaluated, such as germination index (GI), allelopathic index (AI), germination speed index (GSI), mean germination time (MGT), mean germination speed (MGS), radicles growth speed index (RGSI). The results show that there is no significant difference in the allelopathy of the plants of the different collection regions. Also was noted that the extracts of Tithonia exhibit an inhibitory action on the metabolism of the two test plants, the tomato being more sensitive to this action. Theses results suggests that the chemical compounds of Tithonia diversifolia present in the leaves, under natural conditions, eliminate individuals or Interfere negatively in the development of plants that settle around them.