The types of extrapyramidal syndrome (EPS) reactions produced by antipsychotic agents and the prophylactic use of antiparkinson agents in preventing EPS are reviewed. EPS are classified as akathisias, dystonias, parkinson-like symptoms and tardive dyskinesia, and have a varied incidence reported to range from 10.6 to 100%. Incidence may vary with age, gender, drug and dosage. The prophylactic use of antiparkinson agents to prevent EPS is controversial. Many psychiatrists believe the effect of EPS on patients is more harmful than the side effects of anticholinergics, whereas others believe that because of side effects, increased cost, greater risk to tardive dyskinesia and improper use, the use of antiparkinson agents cannot be justified. Most studies of prophylactic use of antiparkinson agents have lacked adequate control groups, adequate blinding procedures for investigators rating EPS, uniform definitions of EPS, random sampling and careful reporting of group characteristics such as dosage and drugs received. There is a lack of definitive studies of the value of antiparkinson agents in preventing the occurrence of EPS in patients receiving antipsychotics. A large, multicenter study should be undertaken to resolve the issue.