Background. Isocitrate dehydrogenase (IDH) mutation status has emerged as an important prognostic marker in gliomas. Currently, reliable IDH mutation determination requires invasive surgical procedures. The purpose of this study was to develop a highly accurate, MRI-based, voxelwise deep-learning IDH classification network using T2-weighted (T2w) MR images and compare its performance to a multicontrast network. Methods. Multiparametric brain MR1 data and corresponding genomic information were obtained for 214 subjects (94 IDH-mutated, 120 IDH wild-type) fromThe Cancer Imaging Archive andThe Cancer Genome Atlas. Two separate networks were developed, including aT2w image-only network (T2-net) and a multicontrast (T2w, fluid attenuated inversion recovery, and T1 postcontrast) network (TS-net) to perform 1DH classification and simultaneous single label tumor segmentation. The networks were trained using 3D Dense-UNets.Three-fold cross-validation was performed to generalize the networks' performance. Receiver operating characteristic analysis was also performed. Dice scores were computed to determine tumor segmentation accuracy. Results. T2-net demonstrated a mean cross-validation accuracy of 97.14% t 0.04 in predicting 1DH mutation status, with a sensitivity of 0.97 +/- 0.03, specificity of 0.98 +/- 0.01, and an area under the curve (AUC) of 0.98 +/- 0.01. TS-net achieved a mean cross-validation accuracy of 97.12% +/- 0.09, with a sensitivity of 0.98 +/- 0.02, specificity of 0.97 +/- 0.001, and an AUC of 0.99 +/- 0.01. The mean whole tumor segmentation Dice scores were 0.85 +/- 0.009 for T2-net and 0.89 +/- 0.006 for TS-net. Conclusion. We demonstrate high IDH classification accuracy using only T2-weighted MR images. This represents an important milestone toward clinical translation.