BACKGROUND The recent adaptation of laser technology in plastic and dermatologic surgery has provided a means to reduce efficiently the irregularities of the surface of the skin. Previous studies have analyzed the short- and medium-term clinical and histologic results of two laser systems: the Sharplan 40C SilkTouch and the 5000C Coherent Ultrapulse with Computer Pattern Generator (CPG). This paper contains the long-term ultrastructural findings observed with the aid of transmission electron microscopy (TEM). METHODS Twenty skin biopsy specimens were taken from ten Caucasion patients, between 54 and 72 years of age, who had undergone facial skin resurfacing with a CO2 laser 1 year previously. The treated areas of the face were divided into two equal parts. One half of the face was treated with the Sharplan SilkTouch laser and the other half with the Coherent Ultrapulse laser. Using TEM, the cell composition of the epidermis was studied ultrastructurally, as were the dermal-epidermal junction (DEJ) and the different fibers and cells in the superficial and middle dermis. RESULTS On the side treated by the Sharplan laser, little melanin was observed, the DEJ was thicker, and there were abundant collagen fibers well compacted in the dermis. Also present was abundant elastin fiber with scarce interstitial spaces. On the side treated by the Coherent, the melanin was abundant and the DEJ was well structured. There were fibroblasts with lax chromatin in the dermis and collagen fibers in the papillary dermis oriented in a vertical and horizontal manner in relation to the epidermis. There was little elastin. The interstitial spaces were abundant. CONCLUSIONS The Sharplan laser system seems to provoke a significantly more intense tissue response, with abundant dermal collagen and elastic fibers. This indicates that the Sharplan 40C SilkTouch might produce longer lasting clinical effects.