Background. The mechanisms of action of laser biostimulation on biological tissue continues to be the object of much scientific research. The positive impact of laser radiation of low and medium power on inhibiting the contraction of blood vessels has already been demonstrated. We decided to investigate the role of angiotensin II in this process. Material and methods. The experiment was performed on isolated tail arteries collected from male Wistar rats. The arteries were first subjected to the effect of phenylephrine (PHE), and then to the effect of laser radiation (10, 30 and 110 mW) in the presence of angiotensin II. Changes in vascular tension were observed and recorded. Results. Laser radiation inhibited the vascular contraction that is typically induced by PHE, proportionally to the power of the laser applied, in both controls and in experimental arteries pretreated with angiotensin II. The KA values calculated for PHE in the presence of angiotensin II and in biostimulated arteries did not differ significantly from controls. Conclusions. Our results suggest that vascular contractility is reduced under the influence of laser biostimulation. The increase in receptor reserve induced by angiotensin II is significantly lowered by the effect of laser biostimulation. Laser biostimulation inhibits the activity of the rennin-angiotensin-aldosterone system by reducing the tissue effects of angiotensin II.