Epidemiological studies on subclinical mastitis (SCM) in the lactating cows were performed with four different diagnostic tests like modified California Mastitis Test (mCMT), somatic cell count (SCC), electrical resistance (ER) and milk pH. Apparently healthy cows had the mean value of SCC, ER and milk pH was 1.49±0.11x105cells/ml, 363.33±15.20unit and 6.62±0.06, respectively, while these values got significantly changed to 19.78±4.99x105cells/ml, 311.67±17.40unit and 7.55±0.04, respectively in SCM infected cows. Different risk factors for SCM like age, parity, season and breed were taken into account in the present study. The results showed that the prevalence of SCM on the basis of mCMT grading was + (56.58%), ++ (34.21%) and +++ (09.21%). The highest prevalence was observed in cows of age group between 3-5 years (53.70%) followed by age group of 5-8 year (28.13%), while lowest in age group of 8 years and above (18.33%). The breed wise prevalence of SCM was found to be highest in exotic breed (42.47%), followed by crossbreed (32.14%), and descriptive breed (25.49%) and lowest in non-descript cows (22.58%). Season also affected the prevalence of SCM, the highest was observed in monsoon or rainy season (43.48%), followed by winter season (31.67%) and lowest in summer season (23.68%). Results of the present study suggested that lactating cows should be screened at regular interval for mastitis to curtail economic losses to dairy farmers.