Angiogram by soft-X-ray and giant histo-sections were used to investigate the interstitial vascular architectures and correlation between vascular reaction and histologic types of naturally occurring mammary adenocarcinoma in old C3H/HeJ female mice. The tumors were diagnosed as adenocarcinoma B type (Dunn's classification) composed of three different histologic types: solid, comedo, and papillomatous. From the findings of the angiograms, the interstitial vascular architectures of the tumor were classified into three patterns: sinusoidal, hypovascular, and hypervascular. The vascular patterns was characteristic in each histologic type and showed a close correlation with the intensity of tumor proliferation. The fine intratumoral angiographic investigation also made clear that necrosis of tumor cells and tissues seen in the histologic types showing marked proliferation was caused by hypoxia. Application of these methods to investigation of the fine vascular architecture in tumors may useful in research for adenocarcinoma.