The assessment of disease activity in Behçet's disease (BD), either by BD Current Activity Form (BDCAF) or Iranian BD Dynamic Measure (IBDDAM), depends largely on the history of the clinical features. Accuracy of recall of a retrospective questionnaire might influence its reliability to some extent. The aim of this study was to investigate whether patients with BD can recall the items included in both of the disease activity forms accurately. Twenty patients with BD completed a retrospective questionnaire that included BDCAF and IBDDAM, twice, 1 month apart. We made some modifications in the IBDDAM, while the BDCAF (revised 8.5.2002, GL) was applied in its original structure. In contrast to the original application of IBDDAM, in which the history obtained depends on the variable time period, all items of IBDDAM in the present study asked subjects to report their symptoms over the preceding 4 weeks. Furthermore, those IBDDAM items for which the operational definitions are not clearly provided by the developers, as well as the items that depend on the objective examination rather than the history, were not included. Concurrent daily data were collected for 2 months via telephone interview. The level of agreement between the retrospective responses and those extracted from daily recordings were quantified for each item using intraclass correlation coefficient (ICC). The agreement between the recalled and daily reports was good (ICCs>0.60) for the majority of items (oral and genital ulceration, skin lesions, arthralgia, arthritis, and eye involvement) included in BDCAF. Exceptions were gastrointestinal symptoms (ICCs<0.40) and headache (ICCs 0.40-0.50). With regard to the IBDDAM, all of the items examined had good agreement (ICCs>0.60), except for headache, for which the agreement was moderate (ICCs 0.40-0.50) for the first and poor (ICCs<0.40) for the second month. For most of the BD-related features questioned in the disease activity forms, patients provided reasonably accurate reports in comparison to information obtained from daily records. However, it should be kept in mind that the limitations of the study design need to be considered while interpreting the results of the present study. Notably, unlike its original application in which the assessment depends on the variable time period, IBDDAM used in the present study assessed the symptoms present during the month prior to the date of assessment. Therefore, our findings regarding IBDDAM cannot be applied to its original use. Furthermore, lack of patients in some of the symptom groups, as well as possible manipulation of recall with daily questioning, might have influenced our results to some extent.