This study was performed to show the feasibility of nuclear magnetic resonance (NMR) techniques for quality evaluation of various agricultural and food products. A real-time in-line NMR quality evaluation sensor was designed, constructed and tested. The device consists of an NMR spectrometer coupled to a conveyor system and a data acquisition system. The conveyor was run at speeds ranging from 0 to 300 mm/s. An NMR signal can be detected when a sample is within ±50 mm of the NMR coil center. The response of NMR sensor was tested using several fruits. The results showed a feasibility of an NMR sensor for evaluating internal quality of various fruits.