Resumo. The present study aimed to evaluate the possible allelopathic activities effects from Araucaria angustifolia on Lactuca sativa germination and initial growth. For this trial, lettuce seeds were used and aqueous extract extracted from the leaves of araucaria, with concentrations of 10%, 7.5%, 5.0% and 2.5%. The effect of the - se four concentrations was compared with distilled water (concentration 0%). Based on the collected data, percentage of germination (G%), germination speed index (GSI), average germination time (t), seedlings length and dried mass were determined. Results showed that aqueous extract from araucaria leaves has an inhibitory property on germination, germination speed index and initial growth in Lactuca sativa.