The herbicide dichlobenil is widely used to control unwanted weeds in non-agricultural areas and aquatic environment. When released into environment, it may harm the growth of algae, which in turn might disturb the balance of aquatic ecosystem. Herein, the physiological as well as the biochemical responses of two fresh water algae, namely Ankistrodesmus acicularis (Chlorophyta) and Anabaena flos-aquae (Cyanobacteria), to different concentrations of dichlobenil were assessed. Parameters, including chlorophyll (a) Content, EC50 values, carbohydrate and adenosine triphosphate (ATP) contents as well as the uptake by both algal species were evaluated. We found a significant decrease in chlorophyll (a) content of both algal species to intermediate and high concentration of dichlobenil, whereas stimulative effect was observed for low concentration of dichlobenil on Chl (a) content. Attainable results derived by probit analysis revealed that the EC50 values at 5th and 7th days were approximate to each other for both algal species. Furthermore, a drastic decrease (98%) in ATP content was noticed at 8.0 mg/L dichlobenil treatment in case of Ankistrodesmus acicularis. On the other hand, the activity of Anabaena flos-aquae cells was enhanced by the application of low and intermediate concentrations of dichlobenil (0.25-4.0 mg/L). Notably, higher concentration level (16.0 mg/L) causes substantial decreases in ATP content. Ankistrodesmus acicularis was found to be more sensitive than Anabaena flos-aquae. The uptake of dichlobenil was best fit to a pseudo-first order rate kinetic. The specific uptake rate constants of dichlobenil in case of Ankistrodesmus acicularis were considerably lower than the corresponding rates exhibited by Anabaena flos-aquae. The half- life time for a given concentrations of dichlobenil was at variance for both algal species. Such variation in the uptake rates and half- life time of dichlobenil for both algal species could have some implications on the aquatic ecosystem.