ObjectiveTo investigate the effect of micro-plasma radio-frequency on the ultrastructure of skin collagen and the level of hydroxyproline in ginea pigs.MethodsFifteen guinea pigs were enrolled in this study. One side of their dorsal skin was exposed to 60 W/10 kJ radiofrequency plasma treatment and the other side was taken as control. Samples were taken immediately, one week and one month after the micro-plasma treatment and examined by light and transmission electron microscopy (TEM), and the level of hydroxyproline content by hydroxyproline assay kit. Results Immediately after the 60 W/10 kJ plasma treatment, the epidermis showed focal lesions, obviously homogenization and complete vaporization loss or degeneration and necrosis of the superficial and middle-level layer derma, and a large area of collagen homogenization. Special staining demonstrated that the micro-plasma beam mainly affected the dermal collagen fibers, forming focal collagen fiber agglutination and degeneration. One week after the micro-plasma treatment, the superficial dermal collagen fibers gradually became into an orderly dense arrangement. One month after the micro-plasma treatment, the superficial collagen fibers showed markedly compact and dense arrangement. TEM showed that the epidermal cells were relatively complete, with normal intercellular structures. But the dermal collagen fibers lost their original normal structure and dermal cells showed disintegration and numerous apoptosis. A small amount of apoptosis remained but collagen structure gradually restored after one month. The level of hydroxyproline after one week was higher than that of before plasma treatment, but the difference was not significant (P>0.05). The level of hydroxyproline after one month was significantly higher than that before plasma treatment, with a statistically significant difference (P<0.05). ConclusionsThe novel micro-plasma radio-frequency technique has obvious stimulating effect on skin collagen. Its main tissue target is dermal collagen tissue. It can stimulate neo-collagen hyperplasia in the skin to a certain degree.