Compudose 200 (Elanco) is a silastic rubber ear implant for beef cattle containing 24 mg oestradiol 17B, Implants are 3 cms long and 4.8 mm in diameter. They are coated with oxytetracycline powder as a local antibacterial and packed in cartridges of 10. The cartridge is fitted to the side of the implanting tool and each Implant is moved into the barrel of the implanter by a “thumb press” on the cartridge. The objectives of the present study were (i) to measure the growth response to Compudose 200 in male calves, growing steers at pasture and housed finishing steers, (ii) to ascertain if there was an additive effect from the use of 300 mg trenbolone acetate (Flnaplix, Hoechst) with Compudose 200 in growing and finishing steers and (iii) to compare Compudose 200, alone or in combination with Finaplix, with other commonly used implant combinations.