Diseases caused by dust containing free crystalic silicic oxide (coal mine pneumoconiosis and silicosis) prevailed by 48% above professional asthma and allergic rhinitis (32%) and diaeases from asbestos (16%) among diseases of respiratory pathways, lung and pleura acknowledged as occupational diseases in the Czech Republic in 2008. The authors deal with current rewiew attitudes and opinions of experts on principles of diagnostics of occupational diseases.