Abstract: The experimental and theoretical studies of the electron screening effects in charged-particle induced reactions at energies of astrophysical interest are summarized briefly. For a deep understanding of electron screening effects, the D(d,p)T reaction has been studied in a series of deuterated metal-, insulator- and semiconductor targets using the 100 kV accelerator of the Dynamitron-Tandem-Laboratorium at the Ruhr- University-Bochum. As compared to measurements performed with a gaseous D 2 target, a large effect has been observed in most metals, while a comparatively small effect is found in the insulators and semiconductors. A reasonable explanation of the large effect in metals is possibly provided by the classical plasma screening of Debye applied to the quasi-free metallic electrons. The subsequent experiments are already in progress to prove this explanation. The data also provided some information on the solubility of hydrogen in the samples.