Corrosion control planning should begin before any well is drilled. The means of controlling corrosion in oil and gas wells are outlined in some detail in this paper. Primary cause of corrosion of metals is contact of metal with corrosive gases in well fluids in the presence of liquid water. Corrosion can be controlled by removing the contact, the corrosive gases or the water. Means for doing this are metallurgy, control of the well environment, separation of the metal of the pipe from the well environment, and cathodic protection. Each should be evaluated for use separately or in combination to obtain the most cost-effective control. Corrosion rates can be monitored by one or several devices which are commonly used for that purpose. The monitoring is especially effective in evaluating the results of corrosion control measures.