This book is an attempt to analysis of feedback queue models with heterogeneous and homogeneous servers.The proposed queue models have been analysed in fuzzy environment. Two different approaches which are alpha-cut and L-R method for triangular fuzzy numbers have been used to evaluate queue performance measures. A comparison between utilization factors using both the approaches has been done at the end of each chapter. The proposed work in this book is very much applicable to daily life situations like as, in super markets, shopping malls, industries etc.