Background: The human parainfluenza and influenza viruses are common causes of respiratory infections in humans. The main goal of this study was to investigate the prevalence of these viruses in health centers of Mazandaran Province, Iran, and comparing their clinical manifestations. Materials and Methods: The sample collection was done using Dacron swabs from the oropharynx of the patients, and the specimens were transferred to the laboratory by Hanks medium. The Viral genomes were isolated by the extraction kits. Then, the reverse-transcription polymerase chain reaction and real-time polymerase chain reaction methods were used for the detection of influenza and parainfluenza viruses' prevalence in the specimens, respectively. Results: Out of 100 samples, 5 specimens (5%) were positive for human parainfluenza, and 24 samples (24%) were positive for the influenza virus. Among all patients, 50 (50%) were female. No human parainfluenza positive patients had croup. While no significant correlation was detected between personality characteristics (sex and age) and the infection with parainfluenza viruses, there was a significant relationship between sex and the detection of influenza virus (P<0.05). Moreover, there was a significant relationship between some symptoms like pain and fever with the presence of the influenza virus and the symptoms such as fever and runny nose with the positive results for parainfluenza in the clinical samples (P<0.05). Conclusion: The results of the study revealed the high prevalence of influenza disease in this region of Iran that calls for taking an appropriate plan for the prevention and control using diagnostic tests like polymerase chain reaction.