Allelopathy is defined as the detrimental effect that one plant causes to another through chemical compounds that are released into the environment; in Peru, the most used species in plantations is Eucalyptus globulus Labill.; despite the recognized utility for various uses in the Andean zone; during the last decades there have been criticisms based on scientific, ecological and emotional arguments, which maintain that eucalyptus deteriorates the soil and water sources; considering these assertions, allelopathy was evaluated through bioassays with aqueous extract of eucalyptus from plantations in four provinces of Cusco: Anta, Calca, Cusco y Quispicanchi; through allelopathy tests carried out with aqueous extract of leaves, tender branches and fruits of Eucalyptus in the germination and growth of seedlings of Amaranthus caudatus L. (kiwicha), Chenopodium quinoa Willd. (quínua), Hordeum ...