The author summarizes the problem of indication of knee joint prostheses first in a general way and then with regard to special features of osteoarthritis and rheumatoid arthritis. He deals in detail with all substantial indication criteria and assesses their order of importance in different basic diagnoses. He mentions also basic contraindications and aspects which deserve attention in relative contraindications. The author emphasizes the relativity of indication of knee joint prostheses and the necessity of an active approach of the patient to surgery and subsequent rehabilitation.

        Key words: indications, knee joint endoprosthesis, osteoarthritis, rheumatoid arthritis