The degradation of basement membranes by tumor cells involves secretion and activation of proteinases, such as the matrix metalloproteinases (MMPs), and results from an imbalance between their inhibitors and activators that are controlled by various growth factors or cytokines, among which TGF-β(1) may be the most intriguing. In order to study the therapeutic effect and molecular mechanism of hyperthermia on aggressive malignant melanoma, the expression levels of TGF-β(1) and Smad4 in B16F10 cells were dynamically analyzed by RT-PCR and western blotting for 24 h after heat treatment, from which time-dependent changes were determined. As expected, the proliferation and invasive ability of B16F10 cells were suppressed strongly by heat treatment. Furthermore, we compared the expression of TGF-β(1) in melanoma mouse models before and after magnetic fluid hyperthermia (MFH) in vivo. After hyperthermia, the tumor growth rate was reduced with a decline in TGF-β(1) protein expression. We conclude that changes in the TGF-β(1) pathway induced by hyperthermia may be an important part of the molecular mechanism involved.