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A profitability index for evaluation of sires on predicted lifetime production of daughters and their progeny was developed from sire evaluations for milk yield, fat yield, and stayability. Indexes of milk and stayability for first lactations were used to calculate proofs for stayability in later lactations. Predicted milk yields were adjusted to the actual age when the records would be made. Breed averages, which are required for the procedure, were calculated from records of daughters of 1192 Holstein-Friesian sires in the Northeast Artificial Insemination Sire Comparison. Proofs for stayability through the first lactation and indexes for stayability in later lactations were used to describe opportunities for genes of the sire to be expressed in a specified year of first or later generations over 15 periods, 13-mo each. These opportunities, when discounted and summed, give the expected number of lactations from one conception. Multiplying the expected number of lactations by milk and fat proofs and net profits per kilogram estimates total economic returns from a single conception. Examples show that stayability may be important in evaluation of sires. The correlation between milk proof and economic evaluation was only .77.