The objective of this study reported in this research paper was to compare the lactation curves of the production of milk, fat, protein, percentages of fat and protein, and somatic cell score in purebred Holstein ( cows and Swedish Red and White ( Holstein ( crossbred cows in the south central region of the province of Cordoba, Argentina. The data set consisted of 32847 herd test records from 1244 purebred H cows and 310 SRW x H crossbred cows, from three commercial dairy farms with cows of firs t to fifth or more lactations. The curves were modeled using the fourth order Legendre orthogonal polynomials. In this study, the data of production of milk, fat production, protein production, percentage of fat, percentage of protein and somatic cell scor e ( were analyzed. Purebred H cows had significantly higher milk production, more fat production and higher protein production levels than did SxH crossbred cows. However, SxH crossbred cows produced milk that had a higher percentage of fat and a highe r percentage protein than did purebred H cows. In none of the lactations did somatic cell score differ significantly between the two breed groups. The results of our study showed that, SxH crossbred cows had significantly higher percentages of fat and prot ein; however, purebred H cows were significantly superior to SxH crossbred cows for the production of 305 d milk, fat, and protein. Mammary health, expressed in SCS, did not differ significantly between the two breed groups. Thus, suggest that crossbreedin g Holstein purebred cows with SRW bulls can improve the composition of milk solids without affecting mammary health and, in this way, compensate substantially for any potential loss in the production and/or quality of the milk of the crossbred cows compare d to H purebred cows.