Introduction: The left atrium (LA) has a significant role in regulating blood flow from veins to the left ventricle (LV). LV performance is affected by several factors including preload, which is partly, but highly, dependent on LA volumes. The aim of the present study is to perform simultaneous assessment of LA and LV volume changes during the cardiac cycle in healthy circumstances. Therefore, LA and LV volumes and volume-based functional properties were determined in healthy adults, and the associations of these parameters were examined. Methods: The present study consists of 164 healthy adults (age: 33.0 ± 12.3 years, 82 males) being in sinus rhythm. All subjects have undergone complete two-dimensional Doppler echocardiography with three-dimensional speckle-tracking echocardiography (3DSTE). Results: Increased end-systolic maximum LA volume was associated with higher LV volumes and reduced LV ejection fraction. Very high early pre-atrial contraction and late diastolic LA volumes were associated with increased LV volumes, reduced LV ejection fraction and increased LV mass. Increased LA volumes were associated with increased LV mass. Higher LV volumes were associated with tendentiously higher LA volumes. Higher LV end-diastolic volume was associated with tendentiously higher all LA stroke volumes (SVs) and total and active LA emptying fractions (EFs). Higher LV end-systolic volume was associated with tendentiously higher all LA SVs but preserved all LA EFs. Conclusions: 3DSTE is capable of simultaneous assessment of LA and LV volumes and volume-based functional properties for (patho)physiologic studies. Moreover, 3DSTE-derived LV and LA volumes and functional properties show strong associations.