Bell’s palsy is a relatively common disease characterized by the sudden onset of unilateral facial paralysis. Using a centralized system that contains demographic data, the authors estimated rates, trends, and demographic risk of Bell’s palsy during a 2-year period. There were 140 incident cases of Bell’s palsy among patients referring to private clinics (a total of 6500 patients). The crude incidence rate was 2.15%. Incidence rates were high in an age range between 20-30 years and were equal among females and males. Incidence of BP was higher in cold season than warm ones and higher in cold regions. The results are consistent with hypotheses regarding viral etiologies (e.g., reactivation of herpes simplex) of Bell’s palsy in which cold can activate this virus.