BACKGROUND Venous leg ulcers (ulcera crurum venosa) are frequently seen in elderly patients. It has been suggested that low level laser irradiation has a biostimulative and wound healing effect; however, this has not yet been clinically verified by controlled studies. METHODS The difference in size reduction of leg ulcers with and without low level laser or placebo laser treatment was measured in 44 patients randomised into two treatment groups (685-nm low level laser and placebo laser) or a control group which served to quantify the effect of laser application. All patients received standardized wound care. OBJECTIVE The aim of the study was to compare the effectiveness of low level laser irradiation with that of a placebo "light source". The size of the ulcers was planimetrically measured at baseline (day 1), at the end of therapy (day 28) and 2 months later (day 90). The difference in wound size was evaluated. RESULTS There were no statistically significant differences in reduction of wound size between the three groups, thus suggesting that low level laser light does not have any stimulatory effect on wound healing in ulcera crurum venosa.