Correlations between metric, cyto- and histomorphological characteristics and thermographical results of 119 carcinomas of the breast have been studied by statistical methods. For the purpose of semi-quantitative evaluation the chi2 of 14 characteristics were calculated from foursquare tables and summarized in a correlation matrix. The study revealed a significant increase of thermographically suspect pictures with increasing size, but this was independent of the depth (i.e. the distance from skin surface) of the tumors. The proportion of uncertain but not clearly suspect results was 35% with the infrared telethermovision method, in contrast to 8% with liquid crystal plate thermography. Thermographically non-suspect carcinomas (especially the negative cases with liquid crystal plate thermography) were rich in connective tissue or stroma in most cases. On the other hand, carcinomas with numerous mitoses, large cell nuclei, increased N/C-ratio and large and strongly stained nucleoli predominantly exhibited definitely suspect pictures. The significant correlation between number of mitoses, size and staining of nucleoli and the thermographic results emphasizes that, besides vascularization and altered thermo-regulatory functions, the metabolism of the tumor itself contributes to the temperature differences. The type of growth and histological grading indicate that tumors with unfavourable prognosis preferentially exhibit thermographically suspect results. The use of thermography as a screening method is restricted because of possible false negative results. On the other hand, its additional use is justified in view of the gain in information about the biological situation of suspect alterations of the breast.