The authors analysed 20-years and longer observations over health state of personnel having occupational contact with highly enriched uranium. Findings are no determined effects as clinical manifestations of chronic uranium intoxication, presented by most frequently involved systems (hemopoietic, bronchopulmonary) and main organs accumulating uranium (liver, kidneys, bones). Long-term observations revealed malignancies in 11% of the examinees. Further medical observations over the personnel (risk group) are required to evaluate risk of aleatory effects in prolonged contact with various uranium compounds.