The objective of this study was to estimate the profit of first lactation and genetic evaluation of Holstein dairy cattle population of Iran. To do that, a total of 219,507 records from first lactation Holstein dairy cattle calved between 2000 and 2011 across 569 herds were used. To estimate the profit for first lactation cows, required economic data were collected from three large dairy farms in Isfahan province as well. In the study, factors affecting on investigated trait were extracted by using the Proc GLM procedure of SAS 9.1 statistical software. Finally, the effect of herd-year-season of calving as fixed effect, and age at first calving (linear and quadrate) as covariate effects were considered in the final model for genetic evaluation. Genetic components were predicted by average information restricted maximum likelihood (AIREML) with an animal model. The phenotypic trend of profit for the first lactation cows was US $ -39.93 per cow per year. This negative trend can be explained by difficult economic conditions of Iran and partially by errors in data recording. The genetic trend of profit for the first lactation cows was US $ 5.31 per cow per year. This positive trend can be explained by intensive selection for high producing milking cows during past years. Because milk sale prices are the main sources of income so that contributed % 78.5 of total. The effects of herd-year-season of calving and age at first calving (linear and quadrate) on the profitability were significant (P 0.01). Estimated heritability of profit was moderate, 0.22, suggesting that it could be treated as a trait per se in future breeding programs to achieve a desirable genetic progress. Key Words: dairy cattle, profit, variance component, genetic evaluation
