A comparative investigation was made of welded tantalum and niobium joints, obtained during argon-arc and electron-ray welding. Recommendations on the welding of these metals by fusion are presented. The characteristics of tantalum and niobium welding are determined by their high melting point and high activity with respect to gases oxygen and nitrogen at higher temperatures. At a higher content of gases there is a substantial change in the mechanical characteristics - the ultimate strength rises during stretching and hardness, plasticity decreases. For example, for niobium, an increase in oxygen content from 0.02 to 0.75 leads to an increase in hardness from HV 100 to HV 350.