<p>The effect of the scale factor on fatigue characteristics and failure mechanisms of drill pipes from aluminum alloy D16T and steel G-105 is studied experimentally. The endurance limit in multicycle tests of samples and the fatigue life of drill pipes in in-situ full-scale tests are determined for both materials. A significant decrease in the fatigue characteristics of the materials is detected in the full-scale tests. It is shown that the drill pipes from aluminum alloys meet the requirements on pipes from steel of strength group G-105 according to API RP 7G and have a significant advantage in the specific characteristics compared to steel pipes.</p>