It is known that chromium became a serious pollutant in various environmental due to its common use in industry and that it is highly toxic effect for soil microorganisms. For this reason, it is important to know the functioning of soil microorganism in ecosystesms which are exposed to chromium for a long time. In this context, it was aimed to compare nitrogen mineralization of contamined and uncontamined soils which were in 3 different regions (Bozluk, Kızılyüksek and Yanıkçam) in Aladağ (Adana) near mine but not effected of it and to reveal possible effects of chromium on microorganism. Nitrogen mineralization of soils (NH₄+-N,NO₃--N) was determined by the Parnas-Wagner method over 42 days (11^th, 26^th, and 42^nd days) at 28oC and under constant moisture. The total Cr content of contamined soils is higher than uncontamined soils except for Yanıkçam region (309,59 mg kg^{- 1}). In each place, mineralization rates of chromium added contamined or uncontamined soils were measured higher than the soils which were contamined. The maximum mineralization rate was observed in uncontamined soils of Kızılyüksek (1.73%) which were not added Cr, the minimum rate was in the soils of contamined soils of Yanıkçam which were also not added (0.36%). Based on the results obtained from the findings of this study, it is possible that ammonium and nitrate bacteria was affected by chromium.