A perspective view to hard-X-ray astronomy.

The present observational and instrumental status of hard-X-ray astronomy, (10 - 200)keV, is discussed. The relevance of observations in this energy range is stressed and a few examples of unsolved observational problems in galactic and in extragalactic astronomy are discussed. In these examples the authors focus on the possibility to solve the problems with observations using detectors of the current generation. In this framework, the performances of the most sensitive hard-X-ray detectors are discussed with particular emphasis on the control of systematic errors.