As many as one in 20 adults have persistent acne, which can prove stubbornly resistant to both over-the-counter creams and washes, and antibiotics.
Some acne does clear up significantly when exposed to UV light, but this is unsuitable as a long-term remedy because of the increased risk of skin cancer.
The new treatment, tested by doctors at Hammersmith Hospital in London, uses light, but removes the potentially damaging UV.
Instead, blue and red light wavelengths produced by a lightbox which the patient, all with moderate or mild acne, used for 15 minutes each day.
At the end of a 12 week period, these patients on average showed a 76% decrease in the number of visible spots on the area treated.
This was better than the other active treatments, although there were not enough patients to make this statistically significant.
And it was much better than simply treating with a box that produced only normal white light.
Dr Tony Chu, who led the trial, claimed that the combination of lights both attacked bacteria contributing to the acne, and promoted healing in the skin.
He said: "Our challenge now lies in incorporating this treatment to more severe cases of acne and finding ways of incorporating this treatment into their therapy."
However, an expert from one of Europe's leading centres researching acne disputed whether the light could have an anti-bacterial quality.
Dr Richard Pojar, director of the Skin Research Unit at Leeds University, said that the state of mind of the acne sufferer could have a pronounced effect on the state of the disease.
He said: "There's no evidence that red or blue light has an anti-bacterial quality - these organisms are used to living in normal light, which has red and blue light in it."
He said that putting any acne sufferer on even a "placebo" treatment - which contains no active ingredient - tended to improve the acne, simply because the improved mental state tended to improve the levels of hormones in the body.
The research was reported in the British Journal of Dermatology.