Data acquisition and reconstruction speed both are crucial for real-time MRI. However, MR image reconstruction speed is highly dependent on the processing capabilities of the hardware platforms (e.g. CPUs, GPUs). Recently, it has been observed that Field Programmable Gate Arrays (FPGA) are a potential candidate to address the computational demands of parallel MRI algorithms. This paper presents the first design effort to implement high performance 32-bit floating-point FPGA-based coprocessor for real-time GRAPPA reconstruction. In-vivo results of 12-channel, 3.0T human-head dataset show that the proposed system speeds up the image reconstruction time up to 106x without compromising image quality.