The estimation of receiver coil sensitivity profiles is required for many Parallel imaging algorithms including CG-SENSE [1]. Conventionally, CG-SENSE uses pre-scan method [2] to estimate the sensitivity maps for which a separate scan is required. This paper proposes the use of GROG [3] to estimate sensitivity maps without any need to acquire a separate scan.CG-SENSE is an iterative algorithm used in PMRI which requires sensitivities of the receiver coils for MR image reconstruction from under-sampled data. GROG [3] has been recently proposed to grid non-Cartesian data sets in a Cartesian fashion. Eigen-value method [4] is an implicit technique of estimating the sensitivity maps using a series of Eigen-value decompositions. The proposed method starts with the acquired radially under-sampled data (cardiac data in this paper). The central region of the acquired data (window size of 24x24 in this paper) is cropped and Grog gridding is applied to get the Cartesian estimate of this data. The inverse FFT of this Cartesian k-space provides a low resolution image. In this paper, the sensitivity maps are estimated from these low resolution images obtained after GROG gridding using (1) Pre-scan method [2] and (2) Eigen-value method [4]. The novelty in this work is the use of GROG gridding on the central region of the acquired under-sampled radial data to estimate the receiver coil sensitivities using Eigen-value method[4]. The reconstructions are performed on cardiac data obtained using 3T Skyra Siemens scanner at Case Western Reserve University, USA which contains 30 channel cardiac coils with 80 measurement frames in radial form 256×144×30 at TR=2.94ms with real-time, free-breathing and no ECG gating. The acquired data is under-sampled for different acceleration factors retrospectively. Artifact Power [5] is used to test the quality of the reconstructed images.Figure1 shows the reconstructed cardiac images for different acceleration factors (AF) using the sensitivity maps estimated from the proposed method with CG-SENSE. Figure2 shows the reconstructed cardiac images obtained using the sensitivity maps estimated from the pre-scan method with CG-SENSE. Figure 3-a and 3-b compare Artifact Power (AP) and PSNR for the reconstructed images. The results show low artifact power and high PSNR (as desired) in the reconstructed images for all the acceleration factors using the proposed method. This shows that the proposed method successfully estimates sensitivity maps without the need of a separate scan providing good reconstruction results.GROG based sensitivity map estimation (proposed method) is an effective method to estimate receiver coil sensitivity profiles without any requirement of a prior scan or body coil image.