Forty-six patients fulfilling the DSM-IV criteria for claustrophobia were assessed with behavioral, physiological, and self-report measures. They were randomly assigned to four conditions: (1) one-session (E1); or (2) five-sessions of exposure (E5); (3) five-sessions of cognitive therapy (C5); and (4) Wait-list for 5 weeks. The first condition consisted of a single 3 h session of massed exposure, and condition 2 and 3 of 5 h of gradual treatment, which was done individually by very experienced therapists. The results showed that treatment was significantly better than the wait-list condition, and the three treatments did equally well with no differences between them. At post-treatment 79% of treatment patients vs 18% of the wait-list controls had improved to a clinically significant extent. When the three treatments were compared 80% in the E1-group, 81% in the E5-group, and 79% in the CS-group were clinically improved. Ar the 1 year follow-up the corresponding figures were 100%, 81%, and 93%, respectively. The implications of these results are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.