The present issue of the "Inzhenerno-Fizicheskii Zhurnal" (IFZh) is thematic; it is devoted to rheology problems. The issue includes mainly materials of papers presented at the XXIst Symposium on Rheology (24-29 June 2002, Ostashkov, Tver' Region) and results of rheological investigations carried out at the A. V. Luikov Heat and Mass Transfer Institute of the National Academy of Sciences of the Republic of Belarus. The good old tradition of publishing thematic issues on rheology problems in the journal is already more than 30 years old. It has contributed to the development of this important trend in scientific research worldwide and in the CIS and has attracted fresh creative forces and made a valuable contribution to science and technology. @ABSATZ6 = The success in the development of rheology was in many ways facilitated by the establishment of the Rheological Society named after A. V. Vinogradov, a bright person and a gifted scientist. The work he started is being actively continued by his talented disciple, V. G. Kulichikhin, Corresponding Member of the Russian Academy of Sciences. I express my thanks to V. G. Kulichikhin, President of the Rheological Society of the CIS, and L. I. Ivanova, Academic Secretary, Cand. Sci. (in Engineering), for their support in creating the thematic issue. May the good tradition of IFZh continue further; let us wish it success. Professor Z. P. Shul'man, Vice-President of the Rheological Society of the CIS, Honored Scientist of the Republic of Belarus