24 outpatient children ages 7-17 who are suffering from an anxiety disorder (separation-anxiety, overanxious disorder, PTSD) will be given challenge dr s, p.o. fenfluramine, p.o. yohimbine, and iv clonidine. These drugs will be u d to stimulate neurohormonal output which will characterize the neurobiology this condition in children. These patients will be compared to 12 normal age/sex matched controls. Outcome variables will be area under the time-pl ma concentration curve for growth hormone, cortisol prolactin and ACTH.