Streptococcus agalactiae is a contagious pathogen in subclinical mastitis affecting dairy farms and causing significant economic losses. This microorganism is able to use different mechanisms to colonize bovine mammary gland and the persistence of infections may be associated with the ability to form biofilm. The aim of this study was to investigate the capsular type and correlated with the capacity to form biofilm in S. agalactiae isolated from milk of cows with subclinical mastitis. Thus, we performed the PCR for genes encoding capsular typing (Ia/Ib-VIII) in 145 S. agalactiae strains. For biofilm assays, we used 96-well polystyrene microplates and the strains were incubated in Tryptone Soy Broth (TSB) at 37°C for 18h without shaking, under 5% CO2 atmosphere. In the current study, all strains were biofilm producers and 83 (57.2%) were Ia capsular type followed 62 (42.8%) type III. Quantitative biofilm evaluation found 85 (58.6%) strong, 42 (29%) moderate, and 18 (12.4%) weak biofilm producers. When evaluated the quantitative distribution among Ia and III capsular type, the results were similar being, Ia - 46 (31.7%) strong, 28 (19.3%) moderate and 9 (6.2%) weak. Considering type III, 39 (26.9%) strong, 14 (9.7%) moderate and 9 (6.2%) weak producers. In our study, we found 2 capsular types and no difference was observed in biofilm formation regarding them, showing that all strains may have the capacity to establish a mammary gland infection with biofilm, independent of capsular type.