Transcranial MR guided cavitation-based Focused Ultrasound (FUS) treatment (histotripsy) is performed in vivo for the first time on a pig brain. Transcranial histotripsy is delivered by an MRI compatible FUS transducer array inside a 3T MRI scanner. Real-time MRI monitoring with 2 second temporal resolution is carried with an intra-voxel incoherent motion (IVIM) pulse sequence synchronized with the FUS array. IVIM images show the histotripsy ablation effect at the intended treatment location in real-time, and the ablation zone was confirmed by post-treatment images. This is the first study to show successful in vivo transcranial histotripsy guided by MRI.