On behalf of the IAU Commission 48 "High Energy Astrophysics" a special session on "CNO Isotopes in Astrophysics" was held at the General Assembly of IAU in Grenoble on August 30, 1976. This topic was chosen since it has recently included many exciting developments in various domains of physics and astrophysics such as for instance meteoritical studies, radioastronomy measurements of the interstellar gas, new determinations of nuclear reactions cross-sections...