This chapter gives a review on the incidence, risk factors and management strategies of the complications encountered in diagnostic and therapeutic neuroendovascular procedures by focusing on both patient and procedure. Complication avoidance in surgical procedures associated with high operative risk and heavy morbidity are summarized into three general measures: (i) making the decision to treat or not to treat, (ii) carefully planning the procedure and (iii) preparing for life-threatening emergencies with alternative life-saving therapeutic measures. Crisis management on the other hand requires thorough knowledge of possible patient-specific and intervention-specific complications, and mastery of their respective treatments. A careful study of patient anatomy will allow the interventionalist to choose his/her tools carefully and plan for alternative solutions in case the initial strategy fails. Operator expertise as well as the support of qualified endovascular and neurocritical care teams is required to ensure a smooth transition from step to step, ultimately leading to optimal patient outcome.