Purpose: To determine the prevalence and intensity of oral impacts on daily performance in 20- to 50-year-olds attending the dental clinic at Tehran Dental School and to investigate the association between the Oral Impacts on Daily Performance (OIDP) score, self-reported oral and general health and clinical findings of oral health. Materials and Methods: The study population comprised 20- to 50-year-olds attending the dental clinic before receiving any treatments. Data were collected using questionnaire-led interviews and clinical examinations. The questionnaire consisted of a validated questionnaire of the Persian version of the OIDP index, sociodemographic characteristics and self-reported general and oral health of subjects. The number of teeth, prosthetic status and the decayed, missing and filled tooth score (DMFT) were recorded according to WHO criteria. Statistical analyses were performed by Wilcoxon test and linear regression modeling. Results: A total of 499 individuals participated in the study. Among the subjects, 82.6% had experienced one or more oral impacts on their daily activities, and 49.5% of impacts were reported to be of severe or very severe intensity. Eating was the performance most frequently affected (50.1%) followed by smiling (16.2%) and sleeping (11.8%). The OIDP score was higher in the participants with a lower wealth index (P = 0.015) and in those with more decayed teeth (P = 0.013). The association between self-reported oral health and OIDP score was of borderline significance (P = 0.05). Conclusion: Oral health status has an enormous impact on the daily performance of Iranian adults attending the dental care center. More emphasis on oral health care in disadvantaged populations, particularly in countries with a developing oral health system, is required. Keywords: OIDP, oral health, oral impacts on daily performance, quality of life, self-assessment