Purpose: The objective of this study was to assess the periodontal treatment needs and the dental status in relation to smoking indicators with special emphasis on lifelong exposure to smoking among 35- to 44-year-old Iranian dentate subjects. Materials and Methods: Data (N = 8276) were collected as part of a national survey using the World Health Organization criteria for sampling and for using the data as clinical indicators. Gender, age, place of residence and level of education served as sociodemographic information, and community periodontal index (CPI) and number of teeth served as clinical measurements. The smoking indicators comprised smoking, duration of smoking (years), daily smoking (cigarettes/day) and lifelong exposure to smoking. Results: In total, 81% of the subjects were non-smokers, and 32% of the males and 5% of the females were current smokers. Maximal CPI = 2 was found among 40% of the subjects, and 53% had maximal CPI ≥ 3. Higher periodontal treatment needs were associated with smoking (P 0.01) in males; CPI = 4 was more frequent (P 0.01) and the mean number of teeth was lower (P 0.01) among groups with higher levels of smoking. Heavy smokers were the most likely to have maximal CPI ≥ 3 (odds ratios, OR = 2.9; 95% confidence intervals, 95% CI = 1.8 to 4.7) and to have 20 teeth (OR = 2.3; 95% CI = 1.5 to 3.6). Conclusions: Smoking and lifelong exposure to smoking with a dose-dependent effect seem to be associated with higher periodontal treatment needs and poorer dental status among the middle-aged, particularly in males and in low socioeconomic groups in Iran. Keywords: dental health surveys, middle-aged, oral health, smoking