Two studies involving 270 yearling steers were conducted to compare four growth promotants (three estrogenic and one androgenic). These represented short, medium and long-acting compounds and were implanted into steers that were grazing natural pasture and were finished in a feedlot. The response (ADG) to the different treatments during the pasture phase of both trials was varied and inconclusive. None of these responses were significantly different from control values and ranged from -6,6% (single implant of Revalor mid-way through the pasture phase, Trial 2) to 13,2% (two implants of Ralgro mid-way through the pasture phase, Trial 1). However, significant gains were recorded during the feedlot phases of both trials and improved gains over control values of up to 30,8% (P < 0,01) were recorded for steers implanted with Revalor (Trial 1).