Abstract In oil wells with beam pumping systems, sucker rods mainly failed by fatigue due to the fact that they operate under cycling tension stresses. Additionally, superficial defects could be generated during handling and operation of the rods, which favor the formation of fatigue cracks and consequently decreasing the original expected life of the rod. Because of a high rate of rod failures by fatigue, and the consequent increase in operational costs, a study was done to obtain experimental data that will be used for the selection and design of the sucker rods strings. Fatigue tests were done for new high strength sucker rods, selected at random in the filed, to determine the endurance fatigue limit. Four kinds of fatigue tests were done: a) the material was tested in the as received condition (normalize and tempering), b) tests were conducted with specimens having a superficial defect simulating a corrosion pit, c) same as b but samples were quenched and tempered. Material characterization was done for all tested rods, including tension, hardness and impact tests, metallographic analysis and chemical composition. The experimental results showed important fatigue differences among the material evaluated, the negative effect of the surface pitting, and the improvement of the fatigue resistance by quenching and tempering the rods. A correlation between the results of impact test, tension test and fatigue test was developed. The findings and conclusions of this study will help the design engineer in the selection process between different sucker rods in the market. Finally, a simpler test method is presented to predict the fatigue behavior between rods of similar specification but from different manufactures.