Mastitis is the most complex and costly disease of dairy cows occurring throughout the world including Ethiopia. A cross-sectional study was conducted from December 2017 to April 2018 with the objectives to isolate, identify and determine antimicrobial susceptibility of Streptococci species in milk from dairy cows with diagnosis of subclinical mastitis, in Bishoftu town, Oromia, Central Ethiopia. A total of 55 milk samples were collected from California Mastitis Tests positive dairy cows. Out of 55 samples taken, 15 samples were positive for bacteriological examination of streptococcal species with the isolation rate of 2(13.3%) Streptococcus agalactiae, 6(40%) Streptococcus uberis and 7 (46.7%) Streptococcus dysgalactiae. Furthermore, the results of antimicrobial susceptibility testing revealed that isolated Streptococci species were highly susceptible to Norfloxacin (86.7%) and Nalidixic acid (40%). However, the isolates were resistant to penicillin (66.7%) and streptomycin (73.3%). Thus, it could be concluded that bovine mastitis due to the Streptococci species, is a major challenge to the dairy producers in Bishoftu town. Moreover, appropriate control and preventative measures must be instituted and dairy farmers and workers must be trained on proper milking and hygiene practices in order to reduce the prevalence of mastitis in the study area. The penicillin and streptomycin-resistant Streptococci species could be a source of serious infection in humans and hence comprehensive studies including molecular characteristics of the drug resistance gene of Streptococci species should be conducted since dairy cattle might serve as a reservoir of infection for humans.