Purpose: To assess the long-term behavior of 980 implants placed in a private practice and evaluate the influence of periodontitis history and smoking habit on implant survival rates. Materials and Methods: A retrospective review of clinical records of consecutively treated patients with Astra Tech implants was conducted. This review included all patients treated between February 1994 and January 2005. Clinical histories were reviewed, and data were gathered on clinical and radiographic examinations. A record was kept on smoking habits, periodontitis history, length and diameter of implant(s), and whether the sinus was elevated. Cumulative survival proportions analysis was performed, and Cox regression multivariate analysis modified for correlated dependent observations was also used, with the implant as the unit of analysis. Results: A total of 323 patients (185 [57.3%] female; mean age, 55.4 ± 15.2 years) received 980 implants. Of the implants evaluated in this study, 71.1% were placed in patients who were undergoing periodontal maintenance care and 38.8% were placed in smokers. The cumulative survival rate was 96.2% at 5 years; 4.3% of implants failed; 57.1% of failures occurred before implant loading. Tobacco use and periodontitis did not affect the risk of failure, and their interaction did not show significance (P = .386). Implants from individuals with many implants and those placed in patients with sinus elevation showed a higher risk of failure (P .05). Regression analysis showed no significant interaction between periodontitis history, tobacco use, and implant failure. Conclusions: Implant placement is an effective and reliable long-term treatment, even in periodontal patients under maintenance care and with a smoking habit. Combined analysis of tobacco use and history of periodontitis showed no significant interaction with implant failure in this sample. Schlagwörter: dental implants, periodontitis, regression analysis, risk factors, survival, tobacco use