There is renewed interest in dairy crossbreeding as a means to further augment farm productivity and profitability. Research experiments have demonstrated the benefits of crossbreeding on animal performance and financial efficiency, exploiting both additive and non-additive genetic effects. The objective of this study was to compare the biological performance of Holstein, Friesian, Jersey, Holstein × Jersey and Friesian × Jersey crossbred cows using commercial dairy herds practicing crossbreeding over a 5-year period. Milk production and fertility information from the national database on 11,808 cows from 40 spring calving dairy herds that adopted crossbreeding between Holstein and Jersey breeds from 2008 to 2012 inclusive were available. Obvious data errors were removed. Least squares means for traits of interest were estimated for purebred and crossbred animals using linear mixed models. Holstein-Jersey first cross cows produced more (P < 0.001) milk solids (heterosis = 6.5%), calved earlier (P < 0.001) as heifers (heterosis = 1.6%), had a shorter (P < 0.001) calving interval (heterosis = 2.1%) and had a higher (P < 0.05) submission rates in the first 21 d of the breeding season (heterosis = 4.5%) relative to their purebred parent breeds. Friesian-Jersey first cross cows had a lower (P < 0.001) somatic cell count (heterosis = 4%), a shorter (P < 0.05) calving interval (heterosis = 2.5%) and a higher (P < 0.01) submission rate in the first 21 d of the breeding season (heterosis = 1.2%) relative to their purebred parent breeds. Results were consistent with findings from controlled experiments. Breed complementarity and heterosis attainable from crossbreeding resulted in superior performance in crossbreds relative to their purebred parents.