Background Behcet's disease (BD) is a chronic systemic inflammatory disease in which early detection of cardiac involvement is essential. The aim of this study was to assess the left ventricular (LV) functions in BD patients using four-dimensional (4D) speckle tracking echocardiography (STE) and to test the correlation between LV dysfunction and the presence of QRS fragmentation. Methods This cross-sectional study included 64 Behcet's patients and 48 healthy volunteers. The BD group was divided into two subgroups depending on the presence (fQRS+) or absence (fQRS-) of fragmented QRS (fQRS). In both groups, left ventricular global area strain (LV-GAS), global radial strain (GRS), global longitudinal strain (GLS), and global circumferential strain (GCS) were obtained with 4D echocardiography. Results GAS, GRS, GLS, and GCS values were significantly different in Behcet's patients and in healthy volunteers. GLS and GAS values were lower in the fQRS+ than in the fQRS- group (-15.8 +/- 1.8 and -17.9 +/- 1.6,P= .001 vs -25.0 +/- 3.1 and -29.2 +/- 4.2,P < .001, respectively). The duration of disease was longer in fQRS+ than in fQRS- patients (120.8 +/- 67.4 vs 71.0 +/- 40.5,P < .001). Multiple linear regression analysis showed that fQRS and disease duration were independent predictors of LV-GAS. Conclusions Four-dimensional STE may be helpful for the prediction of early cardiac dysfunction in patients with BD. The presence of fQRS may be an indicator of subclinical LV dysfunction.