Forty patients with phobia for injections and venipunctures, fulfilling the DSM-III-R criteria for simple phobia, were assessed with behavioral, physiological, and self-report measures, They were randomly assigned to either 1 or 5 sessions of exposure treatment. The 1-session treatment lasted a maximum of 3 hours, and the 5-session treatment 5 x 1 hr (as maximum). Average treatment time was 2:00, and 3:32 hours, respectively. Results showed that both groups improved significantly on all measures, and approximately to the same extent. Furthermore, the effects were maintained at the 1 year follow-up. Applying stringent criteria for clinically significant improvement showed that 80% in the 1-, and 79% in the 5-session group were clinically improved at post-treatment, while 90% and 84%, respectively, were so at follow-up. It is concluded that 1-session of exposure is the treatment of choice for injection phobia.