Background. The aim of this study was to investigate the impact of different doses and methods of applying low-power laser radiation (810 nm, 125 mW/cm2) on acetylcholinesterase (AChE) activity in human red blood cells. Material and methods. A suspension of human erythrocytes was irradiated with near-infrared laser light (810 nm, 125 mW/cm2) at different energy doses. AChE activity was measured by spectrophotometry. Km and Vmax were estimated with a Lineweaver-Burk graph, and compared with the results obtained for a non-irradiated control sample. Results. Near-infrared low-intensity laser radiation stimulated AChE activity. A fractionated dosage of energy with a larger dose applied first caused a statistically significant increase in AChE activity, more than the same dose applied continuously. Conclusions. Low-intensity near-infrared laser radiation caused AChE activity to change in a manner dependent on energy dose and the manner of energy application. The largest increase in the maximum velocity of the reaction was observed for continuous 9J. When fractionated doses (6J+ 3J and 9J+ 3J) were used, a larger increase in maximal reaction velocity was observed than for the continuous dose of 9 J or 12 J.