The influence of replacement rate (R), price (c/kg carcass weight) and two production systems on total herd efficiency was investigated. R was assumed to be either 15% (minimum), 19% (point in between) or 23% (maximum). Percentage differences (minimum, point in between, maximum) in beef prices for the period 1984 to 1992 (RSA Livestock and Meat Statistics) were calculated for eight-month-old weaners vs. cull cows and 18-month-old market animals vs. cull cows, respectively. These percentage price differences were used to calculate relative income per hectare (1/ha) for two production systems, namely, an 8/18 month system (steers sold at eight months of age/surplus heifers sold at 18 months of age) and an 18/18 month production system (all market animals sold at 18 months of age). From the results it was clear that maximum R is applicable on systems where cull cows are, on a per-animal basis, of higher value than both eight-month-old weaners and 18-month-old market animals. Comparison between the two production systems based on adjusted I/ha and 20% R (assumed as standard practice in South Africa) has shown the 18/18 month system to be more efficient. This study also indiÂ¬cated that longevity is not important for maximizing efficiency, since R should be maximized.