The study was conducted to compute the persistency values of the animals in different lactation periods with various methods drawing upon 3695 test day milk yield of 182 lactations of Brown Swiss cattle in Konya Konuklar Agricultural Enterprise. The computed persistency values of the animals in the first lactation were different (P<0.01) from the other lactations. Lactation number (P<0.05) and calving seasons (P<0.01) effected persistency values. The phenotypic correlation of the methods within the group and with lactation milk yield, lactation period, daily average milk yield and daily maximum milk yield were highly significant (P<0.01). The Solkner and Fuchs’s model based on standard deviation of 305 d lactation period showed the highest phenotypic correlation for lactation milk yield (LMY), daily average milk yield (DAMY), daily maximum milk yield (DMMY), and the best fit to the data collected from Brown Swiss cattle and allowed a suitable description of the shape of the lactation curve. © GSP, India.