Viridans group streptococci (VGS), normal inhabitant of oral cavity, are involved in a number of oral and extra-oral diseases. Among oral diseases, dental caries is the most common public health problem throughout the world. The cariogenicity of oral streptococci is attributed to their acidogenic potential and glucan (extracellular polysaccharide) production. For the study, 552 subjects were selected at random from different localities of Karachi, Pakistan. The subjects were categorized as carious (29.5%, 163) and non-carious (70.5%, 389) with respect to prevalence of dental caries. The carious and non-carious subjects were further categorized with respect to sex and sociodemographic characteristics i.e. age (<20, 21-40, 41-60, 61-80 and 81-100 years), socioeconomic status (SES) based on monthly income (low, middle and high), marital status (married and unmarried), dietary habits [daily consumption of vegetable, meat, fruit, mixed diet (vegetable and meat), milk and milk products], use of tobacco products, use of betel quid products, chewing habits, use of tea and oral hygiene practices. Overall, the prevalence of dental caries was found higher in males (58.9%, 96/163) as compared to females (41.1%, 67/163). The same higher trend of prevalence of dental caries was observed for all categories with respect to sociodemographic characteristics except age where prevalence of dental caries was higher in female of 61-80 years age group. In the present study, 525 isolates belonging to 09 different species of VGS were obtained from oral cavity of 552 subjects. Streptococcus anginosus was the most abundant (53.5%) followed by S. mutans (14.5%), S. mitis (11.4%), S. uberis (6.5%), S. intermedius (4.6%), S. sanguinis (3.8%), S. oralis (3.4%), S. salivarius (1.3%) and S. acidominimus (1%). A preliminary screening to determine the glucan producing potential of all isolates of VGS was performed. Out of 525 isolates, 41.5% were glucan producers while 58.5% were glucan non-producers. Species-wise comparison revealed the highest frequency of S. mutans (80.3%) exhibiting glucan producing potential followed by S. oralis (61.1%), S. intermedius (50%), S. anginosus (36.7%), S. mitis (35%) and S. salivarius (14.9%). None of the isolates of S. uberis and S. acidominimus showed the ability to produce glucan. The frequency of isolates having glucan producing potential was observed higher from carious subjects (46.3%) as compared to non-carious subjects (39.1%). Whereas, species-wise distribution of isolates indicated that the prominent glucan producing species were S. sanguinis (100%, 3/3) and S. mutans (76%, 22/29) from carious and S. mutans (83%, 39/47) from non-carious subjects. The glucan producing potential of VGS was also estimated quantitatively. S. sanguinis produced largest quantity (276.2 mg mean, 206.2-324.6 range) followed by S. mutans (143.5 mg mean, 43.5-521.1 range). The antibiotic susceptibility pattern of 525 isolates of VGS was also evaluated against 24 antibiotics viz., penicillin, amoxicillin, cephalothin, cefazolin, cefotaxime, ceftazidime, imipenem, chloramphenicol, clindamycin, trimethoprim, azithromycin, erythromycin, clarithromycin, ciprofloxacin, levofloxacin, doxycycline, tetracycline, gentamicin, streptomycin, tobramycin, teicoplanin, vancomycin, rifampin and linezolid. The highest incidence of resistance (48.4%) was observed against erythromycin. Overall, 39.2% isolates were susceptible to all the antibiotics used for the study. The emergence of multi-drug resistance (MDR) was noted among remaining 60.8% isolates. The resistance rate was observed as 5.5% isolatesresistant to 1 antibiotic, 4% isolates to 2 antibiotics, 6.3% to 3, 3.2% to 4, 2.5% to 5, 5% to 6, 2.9% to 7, 2% to 8, 4.2% to 9, 1.7% to 10, 2.1% each to 11 and 16, 2.7% to 12, 6% to 13, 2.9% to 14, 4% to 15, 2% to 17, 0.4% each to 18, 21 and 24, 0.8% to 19 and 0.2% to 20 antibiotics. In the present study, the in vitro antibacterial activities of oil, aqueous infusion and aqueous decoction of clove buds (Eugenia caryophyllata) and aqueous infusion and aqueous decoction of miswak (Salvadora persica) were determined against isolates having glucan producing potential viz., S. anginosus (19), S. mutans (10), S. mitis (14), S. intermedius (10), S. sanguinis (10), S. oralis (10) and S. salivarius (07). The highest antibacterial activity was noted for clove oil as all the isolates were found susceptible. It exhibited strong antibacterial activity against S. mutans (20.2mm mean zone of inhibition±3.4SD) from carious subjects and S. sanguinis (17.7mm mean zone of inhibition ±1.1SD) from non-carious subjects. The aqueous decoction of clove buds exhibited the highest zone of inhibition against S. mutans obtained from carious subjects (16.8mm±3.4SD) followed by non-carious subjects (14.3mm±2.3SD). The aqueous infusion of clove buds showed the highest zone of inhibition against S. mutans isolated from carious (13.2mm±3.2SD) and non-carious (13.6mm±4.2SD) subjects. Aqueous infusion and aqueous decoction of miswak failed to inhibit the tested VGS. The MICs and MBCs of the clove oil, aqueous infusion and decoction of buds of clove against VGS was recorded as 5 – 0.625%, 5% and 5 – 2.5%, respectively. The effect of clove oil and aqueous infusion of miswak was also evaluated on glucan production. The VGS isolates producing large amount of glucan were selected for the study. The effects of different concentrations of clove oil (0.5%, 0.25%, 0.125%, 0.0625% and 0.0313%) and aqueous infusion of miswak (10%, 8%, 5%, 2.5%, 1.25% and 0.5%) was assessed for the synthesis of glucan. The different concentrations of herbs preparations exhibited varying degree of reduction in glucan production. Clove oil was more effective and reduced the formation of glucan to approximately 80% in a dose dependent manner.