The involvement of magnetic fields in basic cellular processes has been studied for years. Most studies focus their results on a single frequency and intensity. Intensity has long been the central parameter in hypotheses of interaction between cells and magnetic fields; however, frequency has always played a secondary role. The main objective of this study was to obtain a specific frequency that allows a reduction in the viability and proliferation of glioblastoma (CT2A) and neuroblastoma (N2A) cell models. These were compared with an astrocyte cell model (C8D1A) (nontumor) to determine whether there is a specific frequency of response for each of the cell lines used. The CT2A, C8D1A, and N2A cell lines were exposed to a magnetic field of 100 µT and a variable frequency range between 20 and 100 Hz for 24, 48 and 72 h. The results fit a biological window model in which the viability and proliferation of N2A and CT2A cells decrease statistically significantly in a 50 Hz center of value window. In addition, the non-tumor cell model showed different behavior from tumor cell models depending on the applied frequency. These results are promising in the use of magnetic fields for therapeutic purposes.