Two types of flooding, unrestrained (with no response prevention) and restrained (with prevention of avoidance responses), were compared in normal students who had acquired an active avoidance which was afterwards extinguished. Skin conductance responses (SCRs) were measured during the different phases of the experiment. SCRs were significantly greater throughout flooding treatment when the subjects (unrestrained) were allowed to make an avoidance response which did not terminate the warning stimulus, but SCRs declined at the same rate during subsequent extinction trials regardless of the type of flooding used. Avoidance responses during the extinction trials declined significantly faster after unrestrained flooding. The two types of flooding produced similarly large proportions of desynchrony (lack of covariation in the cessation of SCRs and avoidances) during the extinction test. Nevertheless, the particular sequence of extinction between SCRs and avoidances was found to be dependent on the type of flooding used. Results are in line with other animal and clinical studies and could be used to derive improvements in exposure methods to treat abnormal avoidances. © 1988 Association for Advancement of Behavior Therapy. All rights reserved.