The effects of cashew nut shell liquid (CNSL) on growth performance, carcass yield, relative weight of internal organs and microbiology of digestive tract of broiler chickens were investigated. Five hundred and forty male broiler chicks at one day of age were arranged in a completely randomized design with six treatments and six repetitions with 15 broiler chicks each. The treatments were: control (T1 -without growth promoter virginiamycin and CNSL); inclusion levels of 0.10mL (T2), 0.20mL (T3), 0.30mL (T4) and 0.40mL (T5) of CNSL/kg of feed; and commercial promoter virginiamycin (T6). At 21 and 40 days of age, body weight, feed intake, feed conversion and viability of birds were similar in all treatments. Carcass yield was higher in the treatment with the growth promoter when compared to the control treatment. There was a linear increase in carcass yield when the level of CNSL was increased in the diet. The relative weight of the intestine was lower in the treatment containing virginiamycin when compared to the treatment without the inclusion of additives. The relative weight of the intestines decreased when the levels of inclusion of CNSL were increased. There was a gradual reduction of Escherichia coli concentration reaching the lowest number on the CNSL level of 0.30mL/kg. It was concluded that CNSL showed similar performance and slaughter yield as the growth promoter and reduced the concentration of Escherichia coli in the intestinal contents.Keywords: feeding, feed conversion, nutrition, vegetable extract 0,10mL (T2), 0,20mL (T3), 0,30mL (T4) e 0,40mL (T5) de LCC/kg de ração e T6 (promotor comercialvirginiamicina Palavras-chave: alimentação, conversão alimentar, nutrição, extrato vegetal RESUMO Um estudo foi conduzido para investigar os efeitos do líquido da casca da castanha de caju (LCC) sobre o desempenho, o rendimento de carcaça, o peso relativo dos órgãos internos e a microbiologia do trato digestivo de frangos de corte. Foram utilizados 540 pintos machos de um dia de idade, distribuídos num delineamento inteiramente casualizado, com seis tratamentos e seis repetições de 15 aves cada. Os tratamentos consistiram em: controle (T1 -sem promotor comercial e sem LCC), níveis de inclusão de