Trans-cranial Direct Current Stimulation has been shown to modulate cortical neuronal activity. Weak constant current is applied to the scalp using electrodes, leading to sub-threshold changes in neuronal membrane potential. Before actual clinical stimulation is performed, such systems are validated by simulating the stimulation and the resulting current flow patterns using finite element solvers. However, the reliability of such models depends upon the accuracy with which the underlying anatomy has been modeled [1]. In earlier studies it has been shown that the current flow patterns within the brain are altered due to the presence of lesioned brain tissues[2]. Here we present the first investigations of the use of tDCS in patients with brain tumors. We created a brain model from MRI scans of a patient who had a left hemisphere Glioblastoma Multiforme tumor, we modeled the resulting brain current flow and also compared the results across different tDCS modalities like conventional, HD-tDCS. Our results demonstrate the effect of tumor on the resulting current flow and the ability to modulate current pattern through the brain. However it is important to understand that tDCS is not being suggested as a treatment modality for brain tumors, but as a tool for management of the co-morbidities associated with brain tumors