Background: Ultrasound is an important method to determine the volume of the gallbladder and check its structure. Considering the variation in the size and volume of the gallbladder in disease and physiological conditions, determining the volume of the gallbladder is clinically valuable. This study was carried out to evaluate the gallbladder volume and its association with patients' demographic data in the Prospective Epidemiological Research Studies of Iranian Adults (PERSIAN) Guilan cohort study (PGCS) population., Methods: In this cross-sectional study, 957 individuals aged 35-70 participated in determining the gallbladder volume by a radiologist based on the ultrasound method. The demographical data were collected using a questionnaire. After fasting for 12 h, the ultrasound was performed with an Ultrasonic device (Sonix SP series) with a 3.5 to 5 MHz probe., Results: The total frequency of gallbladder lesions was 2.2%. The results showed a significant association between marriage and gender with the presence or absence of lesions in the studied participants (P < 0.05). Also, significant differences were reported between the volume of gallbladder and gender, body mass index (BMI), social and economic status (SES), metabolic equivalent of task (MET), history of cardiovascular disease (CVD), and hypertension (P < 0.05). The results of a linear regression represented a significant association between gender, BMI, MET, and CVD and the mean volume of the gallbladder (P < 0.05). However, there was no significant association between the presence or absence of a lesion and the individuals' average gallbladder volume (P > 0.05)., Conclusion: According to our results, gender, BMI, MET, and CVD were significantly associated with gallbladder volume., (© 2023. The Author(s).)