This study was conducted to investigate the effect of natural plant extract (NPE) on the growth performance and feed conversion efficiency in beef cattle. Growing crossbred steers were fed pasture hay ad libitum and 2.5 kg/day for two months, then 3.0 kg/day for a further four months, of a maize/soya bean based concentrate. Half the steers were offered a supplement of a dried extract of a mixture of NPE at the rate of 6 g supplement per kg of concentrate. By comparison with the steers fed the control concentrate supplement, those fed the concentrate containing the NPE had better weight gain (P<0.05). During the fifth and sixth month of the experiment the efficiency of use of feed for liveweight gain increased significantly (P<0.01) in the cattle fed the supplement containing NPE compared to those fed the control supplement. It will be of interest to determine the nature of the active component(s) of NPE which is/are responsible for mediating the effects on growth performance in beef cattle in further study.