In a prospective, randomized study, we have examined the effects of pr
eoperative and preinduction positive suggestion on postoperative emeti
c sequelae. A total of 226 patients were allocated randomly to receive
either positive suggestions or no suggestions. Those patients in the
positive suggestion group were told before operation and on induction
of anaesthesia that postoperative emetic sequelae would be greatly red
uced by the use of two antiemetic drugs. Control patients were simply
asked to participate in a study of postoperative well being with no me
ntion of nausea or vomiting. Nausea, vomiting or retching, and antieme
tic administration were measured in the first 24 h after operation. An
tiemetic administration in the positive suggestion group was 16.5% les
s than in the control group (P = 0.03) but there was no significant di
fference between the groups in nausea or vomiting-retching.