Purpose: The aim of this retrospective study was to evaluate results and complications in sinus floor augmentations performed in the presence of antral pseudocyst. Materials and Methods: Two hundred thirtyfive sinus floor augmentation procedures performed in 179 patients (102 men and 77 women; mean age, 46.3 years; range 24 to 77 years) were included in the study. All patients had been admitted between 2007 and 2010 and treated with sinus augmentation in a single-stage or two-stage procedure using lateral sinus floor elevation (LSFE) or in a single stage via osteotome sinus floor elevation (OSFE). Results: A total of 29 (16.2%) patients had 32 (13.6%) sinus floor augmentation procedures performed in the presence of an antral pseudocyst. Faint dome-shaped radiopacities were detected at the floor of the antrum of these patients. No sinus membrane tears occurred during elevation in the LSFE group. Two patients in the LSFE group and one patient in the OSFE group developed acute sinusitis during the postoperative period and were treated with medical therapy. No symptoms of acute sinusitis or any other complications were encountered in the remaining patients after an average 17-month follow-up period. Conclusions: Pseudocysts of the maxillary sinus may not be a contraindication for sinus augmentation by OSFE or LSFE techniques. However, detailed evaluation of patients is crucial to prevent undesirable complications. Further studies of larger patient populations are needed to reach definitive conclusions. Schlagwörter: maxillary sinus, pseudocyst, sinus elevation