The growth and metastatic behavior of five human glioblastoma multiforme xenografts and nine human xenografts of various histological types were compared in severe combined immunodeficient (SCID) mice. The results demonstrate that the metastatic behavior of the human glioblastoma multiforme xenografts did not differ significantly from a variety of other histological xenografts when evaluated at the same transplantation site in the SCID model. These results are consistent with the hypothesis that the site of glioblastoma multiforme growth influences the extraneural metastatic spread of this disease and lead the authors to suggest that the clinical rarity of distant metastasis is not a fundamental property of these cells. A total of 340 male 7- to 8-week-old SCID mice received subcutaneous transplantation of tumor fragments (21-25 mice per tumor type). The tumor-bearing leg was amputated when the tumor reached a volume of 500 mm3; mice were observed for up to 5 months. There was a trend for a lower take rate, longer latent period, longer volume doubling time (VDT) and growth time (GT) in glioblastoma multiforme as opposed to carcinoma and soft tissue sarcoma xenografts. The highest local recurrence rates (78% and 68%) were observed in two glioblastomas multiforme. Both the glioblastoma multiforme and the other histological xenografts exhibited a widely varying metastatic rate: no correlation was demonstrated between VDT, GT, local control/recurrence, and distant metastasis. These findings show SCID mice to be an attractive model for further biological and preclinical studies of human glioblastoma multiforme.