METHODS Data of all (239) patients suffering from thyroid carcinoma and operated on between January 1st, 1982, and December, 31st, 1997 in our center, were analyzed retrospectively with respect to age- and sex-distribution in relation to the histological type of cancer. The change of frequency in the histological groups was observed over a 16 years period. RESULTS From all 239 cases, 202 (84.5%) were females and 37 (15.5%) males. The most common histological type with 70.3% in both male and female was the papillary carcinoma, followed by follicular carcinoma with 21.6% of male and 17.8% of female patients. A medullary carcinoma was seen in 8.1% and 5.9%, respectively and an anaplastic carcinoma in only 5.9% of female patients. There was no significant gender difference regarding the histological type. In male patients there was also no influence of age on histological groups. Females with papillary and medullary cancer were significantly younger than those suffering from follicular and anaplastic cancer. Beside, we observed an increase in papillary and a decrease in anaplastic carcinoma during the examination period. CONCLUSIONS Although the relation of 1 male to 5 females with thyroid carcinoma shows a clear dependence on sex, the histological type distribution is identical in both male and female. Therefore, several different factors seem to influence the development of thyroid carcinoma. One of these factors depends on sex and supports an increased development of carcinoma in female patients. Another factor doesn't depend on sex and causes different histological types. Causes for that could be as well hormonal and reproductive ones as regional differences in iodine availability.