This paper describes experiments on passive Multiple-Input Multiple-Output (MIMO) transmission with load modulation. PIN diodes are used as the variable impedance element at the tag side to realize multi-level modulation. The results indicate that the transmission rate of passive MIMO is up to 2 times higher than that of Single-Input Single-Output (SISO) with the same transmission power when the distance between the reader and the tag is 0.5m. Also, when the distance is 1m, MIMO offers up to 1.7 times higher transmission rate than SISO. These results indicate that passive MIMO offers high-speed data transmission even when the distance is doubled.