Phased-multiple-input multiple-output (phased-MIMO) radar using one-dimensio- nal transmit arrays has been thoroughly investigated in the literature. In this paper, we consider two-dimensional phased-MIMO radar array which is called planar-phased-MIMO radar. This new technique aggregates the advantages of the linear-phased-MIMO radar without sacrificing either the main advantage of the planar-phased-array radar, which is the coherent processing gain, or the main advantage of the planar MIMO array radar, which is the diversity processing gain. The essence of the proposed technique is to partition the planar transmit array into a number of planar subarrays that are allowed to overlap. Then, each subarray is used to coher- ently transmit a waveform which is orthogonal to the waveforms transmitted by other subarrays. Coherent processing gain can be achieved by designing a weight matrix for each subarray to form a beam towards a certain direction in space. Moreover, the subarrays are combined jointly to form a planar-MIMO radar resulting in higher angular resolution capabilities. Substantial im- provements is offered by the proposed planar-phased-MIMO radar technique with respect to the linear-phased-MIMO, planar-MIMO and planar-phased-array radar techniques. The achieved improvements are demonstrated analytically and by simulations through analyzing the corre- sponding beampatterns, the resultant peak side lobe level, mean side lobe level, and directivity. Both analytical and simulation results validate the effectiveness of the proposed planar-phased- MIMO radar.