A trial was conducted to study the effects of the aromatic plant thyme, a commercial probiotic (Protexin) and avilamycin on broiler performance, blood biochemical parameters and also the antibody response to sheep red blood cells. A total of 750 broilers were assigned into five replicate groups for each of five dietary treatments, namely; control (C), 2.5 mg/kg avilamycin (AB), 0.1 g/kg commercial probiotic (P), 5 g/kg ground thyme (T1), and 7.5 g/kg ground thyme (T2). In general, body weight, feed consumption and feed conversion ratio were not affected by dietary treatments compared to the control birds (P>0.05). Birds fed the P supplemented treatment had the greatest serum protein levels (P