Abstract: This study was aimed to estimate current levels of pollution indicator as well as many groups of human pathogenic bacteria and their seasonal variations in different locations of Cauvery river, South India. The samples were collected from 16 different sites along river from Stanley reservoir to estuary regions (Bay of Bengal). The microbiological scrutiny was performed during monsoon (2007), Winter, Summer and Spring (2008) seasons taken for the bacterial analysis of Total Viable Counts (TVC), Total Coliform counts (TC), Total Streptococci counts (TS) and also four different types of pathogenic bacterial load were counts, which are indicator organisms of pollution studies. Total viable counts were found in the range of 6.2-26.0 (x104) mL-1 in monsoon, 5.2-20.0 (x104) mL-1 in summer, 4.0-17.9 (x104) mL-1 in winter and 3.3-15.5 (x104) mL-1 in spring. The TC was found in the range of 4.1-21.0 (x103) mL-1, 3.6-17.0(x103) mL-1, 2.9-14.1 (x103) mL-1 and 2.3-12.0 (x103) mL-1, for TS, it was 4.3-18.0 (x102) mL-1, 3.2-13.0 (x102) mL-1, 2.6-11.0 (x102) mL-1 and 2.0-9.6 (x102) mL-1 during monsoon, summer, winter and spring, respectively. Counts of EC, SA/SH, SF and PA were in the range of 300-3700 mL-1, 20-280, 20-270 and 40-490 mL-1, respectively. The Cauvery river basin has been facing severe anthropogenic activities, mostly due to religious belief, dense population, municipal sewage and industrial waste confluences etc. A huge bacterial gene pool was obtained after this study which was indicative of immense bacterial diversity in the region.