The research was conducted in 2008–2010 in Krakow. The experiments were located close to three busy streets of the city: Mickiewicz, Igołomska and Lublanska Avenue. 16 objects were set up at each location (2 variants in 8 replications). The experimental objects were pots with kentucky–bluegrass, Alicja c.v. 24 pots contained the plants which before sowing were stimulated with a green light emitted by the laser diode, three times for 30 seconds, whereas the remaining 24 pots were sown with red fescue sowing material without previous irradiation. The experiment aimed at determining the effect of pre–sowing stimulation of kentucky–bluegrass seeds with a laser diode on heavy metal contents. After three years of kentucky–bluegrass exposure along the streets in Krakow a smaller soil pollution with heavy metals was assessed in the pots sown with the grass sowing material which was pre–sowing stimulated with the laser diode. Computed bioaccumulation coefficients (BC) revealed that the kentucky–bluegrass which was pre–sowing stimulated with the laser diode accumulated higher quantities of all analyzed heavy metals than the plants which were not stimulated before sowing. Bioaccumulation coefficients (BC) calculated for plants not stimulated pre–sowing included in the range: 0.254–0.561 Zn, 0.434–0.512 Cu, 0.029–0.043 Pb, 0.178–0.211 Ni and 0.047–0.076 Cr, while for plants stimulated pre–sowing laser diode ranged: 0.341–0.849 Zn, 0.623–0.680 Cu, 0.043–0.071 Pb, 0.269–0.341 Ni, 0.063–0.128 Cr.