The theory of evoIution is an important issue in the works of Stanislaw Lem, the science-fiction writer. His vision of evolution comprised in his works can be compared to Richard Dawkins' opinion on evolution in his 'The blind watchmaker' or 'The selfish gene. Their ideas are similar: evolution is based on mutations, i.e. errors in hereditary information. Evolution is not able to predict anything, natura! selection eliminates genotypes of lesser adjustment. Our bodies are not essential for evolution, what counts is only the genetic code included in the cells. Carcinoma, old age and death are the consequence of the evolutionary process. The structure of the human brain also reflects decisions made by evolution for million years. Today we want to improve our imperfect bodies. The advancement in such fields as tissue and molecular engineering, transplantology, nanotechnology, cloning, can assure us that we are close to our goal. However, Stanislaw Lem warns us against excessive interference in our bodies. According to his opinions, ethical considerations should accompany development of science, and especially processes of auto-evo!ution of homo sapiens species.