The Behçet's Disease Current Activity Form (BDCAF) is a clinical instrument used to assess the activity of Behçet's disease (BD), which was originally developed in English. The aim of the present study was to perform a cross-cultural adaptation of the BDCAF to Brazilian Portuguese language and to evaluate its reliability in a population of Brazilian patients with BD. Brazilian Portuguese version of the BDCAF, named BR-BDCAF, was obtained according to established guidelines. Forty Brazilian patients with BD diagnosed according to the International Study Group for Behçet's Disease criteria were assessed by two rheumatologists in independent sessions and submitted to the BR-BDCAF. Inter- and intraobserver agreement were then evaluated by kappa scores (values higher than 0.6 indicated good agreement). Good inter- and intraobserver agreements were achieved for the most common manifestations of BD: kappa scores higher than 0.6 were obtained for oral and genital ulcerations, skin lesions, and articular and general complaints. Moderate interobserver agreement was obtained for ocular activity (kappa 0.483) and fair interobserver agreement was obtained for gastrointestinal (kappa 0.322), major vessel (kappa 0.281), and central nervous system activity (kappa 0.304). BR-BDCAF was found to be a reliable instrument for the classic mucocutaneous and articular manifestations of BD and for general complaints, but complementary assessment is needed to evaluate specific visceral involvement for disease activity.