This report contains results of a test program concerning corrosion fatigue studies of drill pipe immersed in circulating drilling mud containing hydrogen sulfide. The work was performed under controlled conditions in a laboratory at The University of Tulsa, using a test cell specifically designed and built for this program. The facility used real drilling mud circulating, in a closed airtight system, over dynamically-stressed drill pipe specimens. A laboratory computer was used to automatically collect data during the tests, which lasted up to 18 days. No significant difference was found in the performance of normalized-and-tempered vs quenched-and-tempered Grade E drill pipe, but quenched-and-tempered Grade X pipe showed exceptionally desirable qualities. Higher-strength pipe proved to be susceptible to rapid failure via hydrogen embrittlement, as expected. But chemical control of the drilling mud resulted in significant improvement in performance. Corrosion coupons made from five different grades of pipe gave nearly identical corrosion rates under a given set of conditions, but in all cases there was a significant dependence of corrosion rate on temperature. No significant degradation of performance was found when a simple water-based non-dispersed mud was replaced by a dispersed water-based mud containing lignosulfonate. Two precursor effects were found which identify poisoning of steel by hydrogen sulfide. Parameters affected were the stiffness of the steel, and its bulk electrical resistance. The second of these two effects shows some promise for use in the field as a test to identify bad pipe, possibly before cracks begin to grow. 17 references, 53 figures, 32 tables.