Sulfate reducing bacteria (SRB) growth induces several important features in the steel/seawater interface such as changes in pH, redox potential, ion concentrations and structure and composition of corrosion product films. These features, absent in abiotic media, produce drastic changes in the corrosion behavior of the metal. In addition to pitting and crevice corrosion, conditions conductive to the enhancement of corrosion-fatigue crack growth and of hydrogen embrittlement can be generated by the metabolic production of hydrogen sulfide by SRB. While SRB produces more hydrogen entry into susceptible metals when compared with similar levels of abiotic sulfides, corrosion fatigue crack growth rates are slower in biological environments than in similar abiotic conditions. Moreover, bacteria also decrease the performance of cathodic protection of steel and protective coatings in marine environments. A review of the literature and recent results from our laboratories involving the use of electrochemical techniques for corrosion assessment, surface analyses and different types of microscopy also are briefly described.