Abstract: The paper reports the ultrastructural changes of 5 cases of basal cell carcinoma. Under EM there were many cells which were closely aggregated. The junctions between the cells were mainly tight and intermediate. In comparison with the normal basal cells, although the desmosomes in basal cell carcinoma were observed their numbers reduced markedly, and they were immature with abnormal structure and low electron density. Individual cells were in mitotic phase. In pigmented basal cell carcinoma there were melanocytes and melanophages. The above-mentioned EM findings suggest that basal cell carcinoma originates from epithelial cells and retains some features of embryonic epithelium.