The stromal fat content in the parathyroid glands and its significance are still controversial. Several methods have also been introduced to evaluate the content in the literature. In an attempt to better understand the significance of stromal fat content, a computer image analyzing system was applied and 62 glands were investigated using routinely processed tissue. Our study revealed that the average stromal fat content was 34.8 +/- 18.7% which was lower than that of other studies. The stromal fat content was correlated with the age, grade of obesity, area of the gland and serum parathormone level; however, no consistent patterns were obtained with other clinical parameters. These results indicate that the change of stromal fat content may be related to the general condition of the patient similar to the change of fat in other organs. However, the decrease of the content may indicate the early change of parathormone secretory activity even if the serum examination shows no evidence of hyperfunction of the glands.