Abstract Several measures of milking rate were taken twice per lactation during 1457 Holstein lactations in five herds. These were taken to determine which variable would be most practical as a field measure of milking rate. Milking rates were estimated by peak flow which has been taken as the standard measure for milking rate, average flow, percent of milk produced in the first 2min of machine milking, and the amount of milk produced through the 1st min, first 1.5min, and first 2min of milking. Variables constructed from possible differences among these last three variables were also assessed. A measurement solely used to indicate rate should be obtainable before the 3rd min of milking. If rate were measured after that time, an increasingly larger number of cows would have completed their milking, and their records would not be considered in determining rate of flow. The percent of milk yielded in the first 2min of machine milking had high phenotypic (.90) and genetic (1.0) correlations with peak flow. Percent 2min milk was as repeatable within lactations and as heritable as peak flow. These four properties plus the ease with which percent 2min milk was obtained indicated that percent 2min milk was an adequate field measure of milking rate.