The present study aimed to investigate the effects of supplementing a bioactive extract from Olea europaea (EOE) in broiler diets on growth performance. For this purpose, 252 1-d broiler chickens (Ross 308) housed in floor pens were randomly assigned to 3 experimental groups (6 pens / treatment, with 14 birds / pen). Animals were fed with a common non-medicated starter diet (mashed) for 21d, and from 22 to 42 d of age with their respective experimental diet (pelleted): a negative control with no additives (C), a positive control with 100 ppm of monensin (M) and the basal diet supplemented with 1000 ppm of an EOE (Lucta S.A., Spain). Feed intake and growth rate were monitored weekly throughout the trial. Data were analyzed as a completely randomized design, with the type of diet used as the main source of variation. The Tukey test was used to make pairwise comparisons between means. Improvement of average daily gain (ADG) was observed from 35 to 42 days of age in birds fed M and EOE diets compared to those fed the C (P<0.01; 102 and 97 vs. 78 g/d respectively). Moreover, feed conversion ratio (FCR) during the last period was significantly lower in broilers fed the M and EOE diets compared to those fed the C (P<0.05; 1.98 and 2.10 vs. 2.50). No significant differences on feed intake were observed among treatments. Performance of birds fed EOE or M was similar throughout the trial. In conclusion, the inclusion of the bioactive extract from Olea europaea has a positive effect on broiler chicken performance.