The 60 Mc/s proton resonance spectrum of 3-chloromercurifuran has been studied and analysed to yield all the proton chemical shifts and the proton-proton and mercury-proton coupling constants. The relative signs of these coupling constants have been determined either by the spin decoupling method or by analysis and it has been shown that all the proton-proton couplings are of the same sign, as are all the mercury-proton ones. The relative signs of the proton-proton and mercury-proton types of coupling constants have not been determined.