BACKGROUND: Cancer registration in Korea has a longer than 30-years of history, during which time cancer registration has improved and become well-organized. Cancer registries are fundamental for cancer control and multi-center collaborative research. However, there have been discrepancies in assigning behavior codes. Thus, we intend to propose appropriate behavior codes for the International Classification of Disease Oncology, 3rd edition (ICD-O-3) for microinvasive tumors of the ovary and breast not only to improve the quality of the cancer registry but also to prevent conflicts. METHODS: As in series I, two pathology study groups and the Cancer Registration Committee of the Korean Society of Pathologists (KSP) participated. To prepare a questionnaire on provisional behavior code, the relevant subjects were discussed in the workshop, and consensus was obtained by convergence of opinion from members of KSP. RESULTS: Microinvasive tumor of the breast should be designated as a microinvasive carcinoma which was proposed as malignant tumor (/3). Serous borderline tumor with microinvasion of the ovary was proposed as borderline tumor (/1), and mucinous borderline tumor with microinvasion of the ovary as either borderline (/1) or carcinoma (/3) according to the tumor cell nature. CONCLUSIONS: Some issues should be elucidated with the accumulation of more experience and knowledge. Here, however, we present our second proposal.