Subclinical mastitis is a multifactorial, complex, and one of the most common and money wasting disease in dairy cattle farming. The objective of this study was to carry out a screening of subclinical mastitis by California mastitis test and to determine the infectious aetiology. A score ≥ 1 was considered positive. A total of 140 udder quarters were clinically examined, from which 135 were screened for mastitis; 42 samples were positive and were subjected to bacteriological analysis. In addition, an antibiotic sensitivity test was done. The prevalence of subclinical mastitis was 31.1% at quarters level and 62.8% in dairy cows, hind quarters were the most infected 34.78% compared to fore quarters 27.27%. The frequency of infected quarters, according to California mastitis test scores +1, +2 and +3, was 7.4%, 14.8% and 8.8%, respectively. The most isolated germs from the samples were coagulase negative staphylococci with a rate of 43.8%, followed by Enterobacter cloacae (8.77%), Enterococcus faecium (7.02%), Klebsiella pneumoniae (5.26%) and Enterococcus faecalis (5.26%). In vitro susceptibility test showed that all the isolates tested were sensitive to neomycin. The trimethoprim, spectinomycin and erythromycin were active against all staphylococci, and had a moderate effect on Enterobacteriaceae. Amoxicillin was inactive against all strains. The prevalence of mastitis was high, which may cause low productivity and economic loss to dairy farmers. Detailed investigation is needed to identify the risk factors. Hence, there is a need to reduce the incidence of subclinical mastitis by adopting preventive and therapeutic measures for better economy of the dairy farmers.