The Spetzler-Martin (S-M) grading scale was developed to assess the risk of postoperative neurological complications after the surgical treatment of arteriovenous malformations (AVMs) of the brain. Treatment-associated morbidity and poor outcomes are particularly relevant to Grade III AVMs and improving the safety while attaining acceptable cure rates still poses a challenge. A multimodal treatment strategy combining surgery, embolization, and radiosurgery is recommended for S-M Grade III AVMs because of the surgical risk. Grade III AVMs are the heterogeneous group that has been further divided into subgroups according to the size, the location in eloquent cortex, and the presence of deep venous drainage. The risks associated with different treatment modalities vary depending on the subgroup, and the rating scales have been further refined to predict the risk more accurately and help determine the most appropriate treatment choice. Previous results for the treatment of S-M Grade III AVMs vary widely among studies, and the treatment modalities are also different in each study. Being familiar with previous treatment results is essential for improving treatment outcomes.