Voluntary culling on low milk yield and the economic returns for herds with a stable number of milk cows was investigated for spring calving dairy herds in the Republic of Ireland. The analysis was conducted at annual involuntary removal rates: 15, 20 and 25% and replacement costs as percent of beef value 94, 126, 157%. Varying cow replacement rate above involuntary removal rate by voluntary culling increased milk sold per cow in year 16 to a maximum of +5 to +10% after practicing a fixed strategy for 16 years. Greatest absolute and relative gains in yield occur from voluntary culling at the lowest involuntary replacement rate. Voluntary culling up to 3 to 8 percentage units above involuntary cow replacement rate maximizes economic returns per cow in herd when the market price for replacement heifers exceeds 150% of their beef value. Maximum voluntary culling may be practiced for prices near or below beef value.