A model was developed for the in vitro and in vivo study of the continuous cell line, TE-671, derived from a human medulloblastoma. TE-671 grew in vitro as sheets of uniform triangular- to spindle-shaped cells with round to oval nuclei and sparse cytoplasm. The in vitro population doubling time was 31.48 hours (h). Mean colony forming efficiency in an agarose medium was 9.0 ± 3.0%;. TE-671 grew subcutaneously in athymic mice as lobulated masses composed of sheets of small uniform cells with round hyperchromatic nuclei and scanty cytoplasm. Perivascular pseudorosettes were commonly seen in early in vivo passage. The in vivo doubling time of subcutaneous tumors was 3.17 ± 1.02 days, with a latency to 500 mm³ of 20.66 ± 1.48 days. The cell cycle time (T_c) was 24 h, S phase was 14 h, G₁ phase was seven h, and G₂ phase was three h. Intracerebral tumors grew as discrete masses composed of diffuse sheets of small anaplastic cells with frequent mitoses and perivascular pseudorosettes. Both in vitro and in vivo chromosome studies revealed modal chromosome counts in the near tetraploid range with the same marker chromosomes as described in the original report of this cell line. The in vitro and in vivo growth of TE-671 provides the best available experimental model for the analysis of the biological properties and chemosensitivity of human medulloblastoma.