The purpose of the study was the evaluation of blood serum concentration of selected free amino acids of collagen (arginine, glycine, glutamic acid with threonine, leucine with isoleucine and alanine) in patients with diagnosed collagen pneumoconiosis caused by industrial dust containing free silica. The group studied consisted of 17 men aged 41 to 60 years with radiologically diagnosed pneumoconiosis as p, q, or r type. The exposure time to silica dust was equal to 17 years on average. The control group consisted of 21 healthy subject, men aged 16 to 59 years. The serum amino acids were isolated using paper chromatography (the cylindrical technique) and quantitative measurements were performed by means of evaluation of absorption of colorful eluates of DYDA complex with cadmium ions. The results obtained were statistically evaluated using the Student t test at 95% probability level. The statistical analysis of results showed important individual variability of amino acid determined and individual variability coefficients were in range 28.7-39.8%. The significant increase of the glycine and of glutaminic acid with threonine levels (36.4% and 62.2%, respectively) and significant decrease in the level of leucine with isoleucine (16.5%) has been stated in patients if compare with the control group. In patients with collagen pneumoconiosis the levels of arginine or alanine remained within the normal range.