The epiphytic communities on the roots of water hyacinth of the river Yamuna (Delhi) were studied for a period of 24 months, together with physical and chemical variables, in relation to a pollution gradient. A total of 267 species of phyto-epiphyton were recorded (77 diatoms, 132 green algae, 32 blue-green algae, 22 euglenoids and 2 each of dinophyceae and chrysophyceae), within a seasonal succession characterised by dominance of diatoms with a shift in dominance to blue-green algae during summer. Among zoo-epiphyton, dominance ciliates shifts to peak of rotifers in summer. A combination of biotic indices (species diversity, richness) and multivariate analysis was employed to assess the impact of urban and industrial waste disposal on physical and chemical profile and biotic communities of the river. Results indicate that community dynamism is attenuated at the more polluted stations, concomittant with an increased predominance of a tolerant assemblage of diatoms and ciliated protozoans. Presence of bioindicator species have also been confirmed. The results presented will serve as a basis for subsequent studies relating to management and surveillance using epiphytic communities on natural and/or artificial substrates.