The initial material for performed studies was constituted by hull and hull-less DH lines of spring barley (Hordeum vulgare L.). The kernels were irradiated with helium-neon laser (He-Ne) in red light spectrum and at the wavelength of 632 nm. Plants obtained in greenhouse conditions were analyzed for blade area and their photosynthetic activity in flag and penultimate leaves (photosynthetic and transpiration rate, photosynthetic gas efficiency). The results indicated a biostimulation effect of laser light, causing an increase of blade area of flag and penultimate leaves. This effect was higher for flag leaves, and exposure to 180 min of irradiation was more effective as compared to 60 min. The reaction observed depended on the kind of DH lines analyzed, and two of them – R63N/14 and R58N/91 increased their blade area more effectively than others. Simultaneously, photo- synthetic and transpiration rate decreased in dependence on time of irradiation and the kind of DH lines used. On the other hand, gas exchange efficiency defined as photosynthetic coefficient of water use (CO2 assimilation / H2O transpiration) increased for all DH lines and laser light exposure as compared to control.