Background and purpose: The aim of this study was to investigate thyroid volume (TV) and its determinants in healthy young adults without present or previous thyroid disease. Materials and methods: The study was performed in a sample of 145 healthy young participants aged 19-29 years, living in an iodine-sufficient area of Dalmatia. Dimensions of the thyroid gland were obtained by ultrasound and used to determine TV. Anthropometric data was collected, and measurements of serum TSH, fT4, Tg, TgAb, and TPOAb levels were determined. Correlations between TV and other continuous variables were determined using the Pearson correlation test, while multivariate linear regression analysis was used to determine the associations of the potential predictors for the TV. Results: TV in men was larger than in women (p=3.53x10-8) and was positively correlated with anthropometric measurements, with the highest correlation coefficient for height (r=0.53, p=6.36x10-12), then body surface area, BSA (r=0.48, p=1.68x10-9), weight (r=0.43, p=8.28x10-8) and body mass index, BMI (r=0.17, p=0.04). Age and cigarette smoking did not appear to be significantly associated with TV (p=0.13 and p=0.95, respectively). Univariate analysis showed TV correlated with fT4 plasma levels (r=0.35, 1.73x10-5), while multivariate analysis showed height and fT4 levels to be important parameters with a significant role in TV. Conclusions: We confirmed previously observed association of TV with sex and anthropometric parameters and reported a significant correlation between TV and fT4 levels. Furthermore, fT4 levels and height were found to be important parameters for predicting TV.