BACKGROUND A combined, dual-wavelength CO2/Er:YAG laser system having the ability to deliver both clean ablation of skin with the erbium wavelength and a simultaneous deeper penetrating subablative thermal pulse of CO2 was developed for full-face resurfacing. The CO2 component can be pulsed from 1 to 100 msec at a power of 1-10 W with the Er:YAG component pulsed at 350 microsec at 1.7 J/cm2 through either a computer pattern generator with 3 mm diameter spot size or through a noncollimated spot ranging from 0.2 to 8 mm in diameter. Our previous study using this laser on the neck using a 4-8 mm diameter spot with Er:YAG fluence at 1.7 J and the CO2 at 5 W with a 50 msec pulse at a frequency of 10 Hz showed a higher degree of overall patient satisfaction, as well as improvement in skin texture and skin color, compared to patients treated with an Er:YAG laser alone. OBJECTIVE This study evaluated the CO2/Er:YAG laser treatment modality in facial resurfacing. METHODS Ten patients were treated with four passes at 1.7 J with a 4 mm diameter spot and the CO2 at 5 W with a 50-msec pulse at a frequency of 10 Hz. Photoaging scores as well as thermal damage and new collagen formation were compared immediately before and after treatment as well as at 2 weeks and 3 months postoperatively. RESULTS The average pretreatment periorbital score was 6.2 The average posttreatment periorbital scores were 4.2 (P =.0239) at 2 weeks postoperatively (32% improvement) and 3.8 (P =.0028) at 3 months postoperatively (38% improvement). The average pretreatment perioral score was 5.9. The average posttreatment perioral scores were 3.0 (P =.0001) at 2 weeks postoperatively (49% improvement) and 3.3 (P =.0009) at 3 months postoperatively (44% improvement). The average pretreatment cheek score was 4.7. The average posttreatment cheek scores were 2.7 (P =.0066) at 2 weeks postoperatively (43% improvement) and 3.8 (P =. 0152) at 3 months postoperatively (36% improvement). The average pretreatment forehead score was 4.7. The average posttreatment forehead scores were 3.8 (P =.0340) at 2 weeks postoperatively (33% improvement) and 3.6 (P =.0147) at 3 months postoperatively (37% improvement). The average depth of collagen measured in the dermis pretreatment was 29 microm. The average depth of collagen 3 months posttreatment was 54 microm. This is an average increase of 25 microm or an 86% increase in collagen (P =.006). The average thermal damage immediately after treatment was 20 microm. CONCLUSIONS The CO2/Er:YAG laser utilized with four passes at the above-mentioned parameters results in a similar degree of improvement as other forms of laser resurfacing with high-energy, short-pulsed CO2 lasers.