A common problem in brain and abdominal surgery is the perioperative substitution of antiepileptic drugs (AEDs) when patients are temporarily unable to take these drugs orally. We searched the literature for clinical trials with patients or healthy volunteers in whom non-oral formulations of AEDs as substitution were tested. Different search engines, handbooks, expert opinion and our own experience, were used. Pharmaceutical companies were approached for recommendations. This led to three categories of replacement: 1. commercial alternative (n = 10) for clonazepam, diazepam, lacosamide, levetiracetam, lorazepam, midazolam, nitrazepam, phenobarbital, phenytoin, and valproic acid; 2. alternatives that must be prepared (n = 6) for carbamazepine, clobazam, lamotrigine, oxcarbazepine, primidone, topiramate; 3. no alternative (n = 7) for ethosuccimide, felbamate, retigabine, stiripentol, tiagabine, vigabatrin, zonisamide. Thus, for a substantial number of AEDs, unofficial perioperative treatment strategies need to be followed for lack of alternatives to oral administration. There is little clinical research addressing the equivalence of oral and parenteral formulas. Perioperative substitution of AEDs is an underestimated problem, and may increase the risk of postoperative seizures.