This study was conducted to determine the effectiveness of the electrical conductivity (EC) method on the diagnosis of subclinical mastitis in dairy cows comparing with somatic cell count (SCC) and California mastitis test (CMT), and also to investigate the effect of these values on the amount of total viable bacteria, density, freezing point, and mineral substances. A total of 386 milk samples collected from quarters of 188 cows at 10 different farms were used as materials. Of the samples, 258 (66.85%) were CMT (+), 85 (22.02%) were CMT (++), and 43 (11.13%) were CMT (+++). The mean EC and SCC were 25.71, 28.02, and 29.63 mS and 249,453, 1,167,058, and 2,108,139, respectively, according to the CMT results. The total viable bacteria counts ranged from 3.4771 to 6.9395, from 3.4771 to 7.3617, and from 4.7782 to 7.5315 log CFU/mL, respectively. The average amounts of mineral substances were 0.65%, 0.70%, and 0.76%; the density values were 1.031, 1.0297, and 1.029; and the freezing points were -0.5281, -0.5285, and -0.5282, respectively. As a result, it has been concluded that EC showed similarity with the CMT and the SCC in the detection of subclinical mastitis; furthermore, its reliability would further increase when used together with the other diagnostic methods.