— This paper presents an analytical model of steady state throughput of the Slow-but-Steady variant of TCP NewReno as a function of loss event rate, average number of segments lost per loss event, average round trip time, and retransmission timeout value. The presented model is based on the approach proposed by Padhye et al. for TCP Reno throughput modeling and extends it by capturing the effect of fast recovery algorithm of the Slow-but-Steady variant of TCP NewReno on throughput and taking into consideration slow start phase after timeout expiration. Validation by ns-2 simulations shows good agreement and accuracy of the proposed model. Keywords- TCP NewReno; TCP throughput modeling; correlated losses