OBJECTIVES: This study was performed to evaluate whether there is the difference of graft height changes in radiographic evaluation in single implants and multiple implants after maxillary sinus floor augmentation with an auto-xenograft mixture. METHODS: The study group comprised 29 patients (16 men, 13 women; mean age, 56.5+/-12.4 years; range, 27 to 87 years) treated at the implant clinic of the Ewha Womans University Mokdong Hospital. They were treated with the sinus floor augmentation of lateral window technique and simultaneous placement of dental implants. Their implants have been evaluated for 42.4+/-10.5 months. To evaluate the height of grafted material, the real implant length was compared with that of panoramic radiography evaluated by a digital caliper (PACS program), and then the real height of grafted material was assumed. SPSS 19.0 was used in statistical analysis. Wilcoxon singed rank test was utilized for P value and Mann-Whitney for statistical significance in the changes of grafted height between single implants and multiple implants. The level of statistical significance was defined as P<0.001. RESULTS: The evaluated graft height in single implants' group decreased to 0.60+/-0.54 mm at the time of delivery (after 7.5 months, P=0.001), in multi-unit implants' group to 0.96+/-0.84 mm (after 6.5 months, P<0.001). The evaluated graft height in single implants' group decreased to 1.11+/-0.75 mm at the last follow-up (after 43.5 months, P=0.001), in multi-unit implants' group to 1.52+/-0.99 mm (after 41.8 months, P<0.001). Mann-Whitney test was used for the difference between single implants and multi-unit implants. There was no difference in two groups at the time of delivery and the last follow-up (P>0.001). CONCLUSION: There was no statistical significance of radiographic graft height after maxillary sinus floor augmentation between single implants and multiple implants.