Alien species contributes to the extinction of native species. Understanding the mechanisms that promote their domain over native species is very important in the search for effective solutions to combat these species; at this point, researches about allelopathic properties of that species are essential. In this way, this study aimed to analyze the chemistry constitution of the foliar ethanolic extract of Eriobotrya japonica (Thunb.) Lindl, as well as infer about its allelopathic actions through two test organisms (Lactuca sativa and Allium cepa). Seeds of test organisms germinated on Petri dishes covered with filter paper soaked with deionized water (negative control) or four concentration of extract (1, 5, 10 and 50 mg.mL-1). In allelopathic assays were measured the germination index (GI), germination speed index (GSI), allelopathic index (AI), radicles growth speed index (RGSI), germination mean time (GMT), germination mean speed (GMS) and radicles mean length (RML). Eriobotrya japonica (Thunb.) Lindl extract shown flavonoids, steroids, saponins and alkaloids in its phytochemical profile and reduced the GI, GSI and AI in L. sativa and A. cepa. In turn, there was a decline in GMS of L. sativa. The extract demonstrated allelopathic properties what indicates that it is one of the mechanisms used by Eriobotrya japonica (Thunb.) Lindl to conquer new environments.