The effect of an industrial effluent on cellular macromolecular composition and indophenol photochemical activity of isolated chloroplasts of rice (Orvza sativa L. C. V. Mushoori) seedlings have been investigated. Each experiment consisted of two parts. One was the effect of various concentrations and the other was the time-dependent changes induced by the undiluted effluent. The total pigments, proteins, and nucleic acids of rice seedlings declined with an increase in effluent concentration and the time of incubation. The loss in contents of macromolecules like deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein was relatively more marked in the root than in the shoot. RNA and chlorophyll (Chl) contents of the seedlings were found most susceptible to effluent stress. Loss in Hill reaction activity measured as photoreduction of 2,6-dichlorophenol indophenol (DCPIP) of isolated chloroplasts could be correlated in a general way with the loss of pigments, proteins and nucleic acids. Diphenyl carbazide- and Mn2+-induced restoration of loss in DCPIP photoreduction suggests that the damage of oxygen evolving systems is the initial site of action of the effluent.