Laboratory corrosion tests are used in many ways. They can provide a simple basis for comparing the severity of corrosion of two or more materials in a simple standardized way. Laboratory testing can also be a convenient means for closely simulating service environments to obtain useful information for materials selection. Finally, laboratory corrosion tests can also be utilized for qualifying materials for specific uses or serve as a basis for lot acceptance during purchase. In some cases, these various uses many become intertwined. This paper serves to examine some of the subtle aspects of laboratory testing involving H2S and environments common to petroleum applications. Several case studies will also be presented including the in sour petroleum production, inhibition of multiphase flowlines, assessment of crude oil corrosiveness, and corrosion under insulation. Keywords: laboratory testing, correlation, oil and gas, multiphase production, corrosion under insulation