Echocardiography plays an important role in the assessment of cardiovascular diseases. The lack of ionizing radiation and portability make it one of the safest imaging modalities. Although two-dimensional echocardiography is widely used to obtain the motion of the heart structures in real-time, three-dimensional (3D) echocardiography allows for scanning of the heart in 3D with unlimited postprocessing geometries compared to 2D. However, the feasibility is limited because of speckle noise, poor quality, limited field of view and missing anatomical structures. The entire heart cannot be imaged in a single 3D echocardiography scan in most cases, and further improvements are needed to solve the problem. This study proposes a point-based rigid registration followed by B-spline non-rigid registration to align 4D echocardiography images obtained from different sonographic windows. The approach was tested on scans obtained from three volunteer participants. The accuracy of registration was visually and quantitatively assessed by delineating the left ventricle in each scan and computing the Dice score overlap metric and the Hausdorff distance mutual proximity measure between the first scan and the rest. The overall results indicate that the proposed registration approach improves the alignment of the images compared to the original scans.