The determination of the furosine (FUR) indicator of the Maillard reaction in commercial infant formulae (IF), follow-on formulae (FF), human milk (N=10) and raw cow milk (N=7) was performed using high performance liquid chromatography with ultraviolet detection (HPLC/UV). A high FUR content was confirmed that ranged from 1320±102.2 to 1550.9±166.5 mg/100 g protein in infant formulae IF and from 931.9±153.8 to 1156.7±104.5 mg/100 g protein in follow-on formulae FF (human milk – at the average below 6 mg/100 g protein). Such a significant difference between FUR values of commercially available formulas is accounted for imperfection of different technologies of manufacturing IF and FF. In dairy products damage caused by heat treatment could be greater as a result of manufacturing processes and storage conditions. Furosine content was used in order to calculate the concentration of blocked lysine. In infant formulas IF’s the blocked lysine levels were found to range from 19.6 to 34% of total lysine. Taking into consideration harmful for health, toxic products of Mallard reaction, the content of FUR should be labelled. In the Authors’ opinion, the content of furosine tolerance should make compromise between that what is theoretical demanded and that what is practical reached (fresh milk powder for all purposes – about 120 mg FUR/100 g protein, FF of producer C – 930 mg FUR/100 g protein). The authors’ suggestion is that the maximum allowable tolerance of FUR should not exceed 700 mg/100 g protein of IF and FF.