A strict pot experiment involving red clover (Trifolium pretense L.) was carried out by means of complete randomization in four replications in 2004, in a vegetation hall at UWM in Olsztyn. The first experimental factor were varieties: Bona - 4n and Dajana - 2n, the second - seed stimulation using He-Ne laser light at surface power density of divergent beam in a plane of free falling: R0 (control - with no radiation), R3 and R6 mW cm(-2) , applied 1, 3 and 5 times. The experiment was conducted using pots of 9 dm3 capacity each. Each pot contained four plants after emergence. During the vegetation of three shoots, red clover plants were subjected to measurements of photosynthetic and transpiration intensity (three measurements after each cut) that were made using a portable gas analyser, LI-COR 6400. The highest photosynthetic intensity was found for clover from the 2nd cut, the lowest - from the 1st cut for both varieties. Dajana cv. was characterized by significantly higher photosynthetic intensity as compared to Bona cv. Better results, in reference to the control, were recorded in objects R6x3 and R6x5 (Bona cv.) as well as R6x1, R6x3 and R6x5 (Dajana cv.). The transpiration intensity was the highest in plants from the 2nd, the lowest from the 1st cut. Significant differences between varieties were recorded, in favour of Bona cv. The highest dry matter yields, that did not significantly differ, were achieved from the 2nd and 1st cuts, but only for Bona cv. Dajana cv. produced the highest yields in the 2nd and 3rd cuts. Seed stimulation using laser light caused significant increase of dry matter yield for three cuts in objects R6x3 and R6x5, for both varieties. Dajana cv. exceeded Bona cv. by over 23% in reference to total yield of dry matter.