Inorganic metals besides their direct toxic effects, carry the potential of causing serious variations on existing ecosystems in receiving waters. Self purification mechanism is vital for the continuity of the existing micro and macro living organisms in the streams. This mechanism is effected from the existence of metals. In this study, interferences of HgCl2, HgSO4, Ni(NO3)(2), CrCl3, CuSO4 - 5H2O center dot K2Cr2O7, ZnSO4 center dot 7H(2)O and Al-2(SO4)(3) center dot 18H(2)O metal compounds on respirometric BOD and related effects on the self purification, are investigated with the representative formations of DO deficit curves. In the presence of these metals, streamwater BOD parameters and related DO deficit curve formations are significantly effected. (c) 2004 Elsevier Ltd. All rights reserved.