This paper presents the analysis of Multiple Input Multiple Output Systems (MIMO) using Space Time Block Codes (STBCs). In the first part it shall give an over view of MIMO systems and the STBCs along with other Space-Time techniques. Later it will discuss the similarity of diversity order between maximal-ratio receiver combining (MRRC) with one transmit antenna & two receive antennas and two transmit & one receive antennas while using STBCs. This discussion will be extended to two transmit & two receive antennas. Simulation results will also be presented.