A diaper wetness detection system includes a diaper, a wetness sensor, an RFID unit, and a transceiver unit. The RFID unit is a battery-less device that receives an interrogation signal transmitted by the transceiver unit. The RFID unit or the transceiver unit are configured to determine if a measurable characteristic, as sensed by the wetness sensor, indicates if the diaper is wet. The measurable characteristic can be a voltage or current indicative of a resistance, capacitance, or impedance at an area sensed by the wetness sensor. The value of the measurable characteristic is different when the diaper is wet versus dry. Comparing the measurable characteristic value to a threshold value or to one or more previously sensed measurable characteristic values enables a determination to be made as to whether or not the diaper is wet. The RFID unit can be detachably coupled to the diaper for simple attachment and removal.