  Astrophysical gamma-ray spectroscopy is an invaluable tool for studying
nuclear astrophysics, supernova structure, recent star formation in the Milky
Way and mixing of nucleosynthesis products in the interstellar medium. After a
short, historical, introduction to the field, I present a brief review of the
most important current issues. Emphasis is given to radioactivities produced by
massive stars and associated supernova explosions, and in particular, those
related to observations carried out by INTEGRAL: short-lived Ti-44 from CasA
and long-lived Al-26 and Fe-60 from massive stars. The observed 511 keV
emission from positron annihilation in the Galaxy and the role of stellar
radioactivity and other potential positron sources are also discussed.

High Energy Astrophysical Phenomena