A novel design for an integrated passive polarization splitter/converter combination is presented. The device consists of a Mach-Zehnder initerferometer with polarization converters in both arms. The device is analyzed using the transfer matrix method and fabricated in InGaAsP-InP. Measurement results show a splitting ratio of approximately 10 dB and a conversion of > 90 %. This device can be monolithically integrated with passive and active components.