Feed, a determining environmental factor, is essential for quality poultry production. Faced with dietary constraints, different non-conventional raw materials have been introduced in poultry rations with the use of fats. The aim of this study was to evaluate the effect of neem oil on zootechnical performance, carcass characteristics and serum biochemical parameters of slow growing broilers; by feeding a test batch with feed containing neem oil compared to a control batch with feed without neem oil. Up to five weeks of age of treatment with respective concentrations of 0.25% (T0.25), 0.50% (T0.50), 0.75% (T0.75) and 1% (T1), the individuals of the T0.50 batch showed the best Consumption Index and a considerable gain in weight compared to the other batches and the control batch. It was also shown that, the treated chickens showed higher gut length and lower heart weight than the controls.