  Spin effects in high energy fragmentation processes can provide us with
important information on hadronization mechanisms and spin structure of
hadrons. It can in particular give new tests to the hadronization models. In
this talk, we make a brief introduction to the different topics studied in this
connection and a short summary of the available data. After that, we present a
short summary of the main theoretical results we obtained in studying these
different topics. The talk was mainly based on the publications [4-8] which
have been finished in collaboration with C.Boros, Liu Chun-xiu and Xu Qing-hua.
