Abstract-Generalized Regression Neural Network (GRNN) is a radial basis function based neural network used for function approximation and prediction. Thanks to its easy modelling structure, and one pass learning, it has been utilized in many applications as an alternative to other prediction methods such as multilayer perceptron (MLP) and support vector machines (SVM). Since the number of neurons at GRNN's pattern layer is proportional to the number of training samples in dataset, increase in memory usage and decrease in computational time will emerge for huge datasets. Therefore, k-nearest neighbour (kNN) and clustering methods such as k-means and hierarchical clustering, etc. have been frequently used for pattern layer size reduction. Pattern layer size reduction may provide not only simplification in structure but also increase in prediction accuracy. In this work, a pattern layer size reduction approach utilizing Angle Based Nearest Neighbor (ABNN) algorithm is proposed for three-dimensional datasets. The proposed method divides training space into specific angles and for each test datum, it searches the nearest training datum within each angle. At the end, there exists a few training data that will be used in GRNN's pattern layer and these training data are similar to the test datum. Performance of the proposed method was evaluated by using fifteen benchmark global optimization test functions and compared with that of standard GRNN and a hybrid method using kNN as a pre-processor. Simulation results show that the proposed method provides 99.33% reduction in pattern layer size and accuracy is also increased maximally to 65.61%.Keywords-Generalized regression neural network, prediction neural networks, nearest neighbor, pattern reduction and reduced dataset.