This paper presents mutual information achieved by a Massive multi-input multi-output (Ma-MIMO) systems on a block Rayleigh-fading Channels. Mutual information represents the highest achievable spectral efficiency (SE) in Ma-MIMO systems. Fast fading causes the loss in SE which is amplified by using multiple transmit antennas. The channel model considered here is block Rayleigh-fading Channels which resembles the practical scenario of cellular communication. Kronecker model is considered for modeling the spatially correlated channels. Minimum mean square error with successive interference cancellation (MMSE-SIC) is implemented to detect the channel and estimate the SE in the Uplink and Downlink channels. The simulation result shows linear MMSE and MMSE-SIC detector’s achievable SE for the Ma-MIMO systems.