The oncologic and genetic characterization of C3H/HeDiSnMvY mice is pr
esented. These mice are homozygous and genetically homogenous by all 2
0 loci of eleven chromosomes studied. The fetal frequency of spontaneo
us tumours in these mice was 35.7% with predominance of malignancies o
f multiple origin. Morphologically they were identified as hemoblastos
es (26.2%), hepatomas (9.5%) and breast carcinomas (9.5%). Tumors were
mainly revealed in mice aged 18-24, months.