Experiments on tearing of a thin current sheet are performed in a collisionless laboratory plasma. The tearing of the finite-dimension current sheet (Lx=40 cm, Ly=100 cm, Lz≈1.3 cm) is fully three-dimensional (3-D). The 3-D tearing is observed to lead to patchy reconnection. The wavelengths of the most unstable mode of the 3-D tearing satisfy the scaling relationship: &lgr;y≈&lgr;x≈30 Lz. The e-folding time of the 3-D tearing is about 50 percent longer than that of the 2-D tearing: &tgr;(3-D)/&tgr;(2-D)≈1.6. The sites of the patchy reconnections are centered on the X line segments which are located in the current density minima. The experimental results are consistent with the observational model proposed by Russell and Elphic (1979) for the reconnection at the dayside magnetopause, known as the elbow-shaped flux transfer events (FTEs). The results also support the theoretical idea that elbow-shaped FTEs can be produced by the 3-D tearing, resulting in patchy and intermittent reconnections driven by the solar wind as proposed by Kan (1988). ¿1991 American Geophysical Union