The produced water used in water injection plants for secondary recovery systems normally has high concentrations of chlorides sulphates iron and microorganisms mainly Sulphate-Reducing Bacteria: SRB. As it is known these kinds of bacteria produce microbiologically influenced corrosion (MIC) which is developed as sulphidric corrosion due to the production of H2S. For these reasons it was considered to evaluate the aggressiveness of this kind of water installing an online monitoring system that simulates the actual conditions of the produced water pipe networks through a simultaneous meassurement of bacterial growth corrosion and biofouling rate biofilm morphology products analysis and morphology of attack. The results obtained show the importance of the online monitoring system to evaluate the correspondence between the keys parameters involved in the MIC process and the corrosion rate. Key Words: Microbiologically Influenced Corrosion Sulphate-Reducing Bacteria Online monitoring system water injection systems.