Sl'~nL\\{Y-,"cltroll/ltsclIlar !Jlockillg actiolls of dia:;cpam awi its interaction with some myonellral h/ockillg agents 7cere stw/ied ill dogs and /1/ humalls undcrr;oillg surgery under r;cneral allllcsthcsia. J)iazepillll alonc had 110 effect Oil the response of tibialis anterior 1Iluscle to illdirt'Ct stimulatioll in dor;s. Ar;aill, diazepam ill a bolus dose of 5 mg did not illfluence a prc-c.ristillr; partial bloc/, hy d-tllhocllrarine, gallamine or panCl/rOllilllll. Bl/t a significallt ill crease ill both the degree and dllratioll of block 7f'as observed 7f'izCIl diazepam and d-tubocurarine 7£'crc r;i7'cn simultancollsly, Sltr;r;csting all agollist action in diazepam. On thc colltrary, simllltaneolls IIse of dia:;cpaJll and gallamine caused a sigllifical/tly less il1tense block of tihia/is mllscle beitch tension as compared to gallamine alonc, suggestinr; all antagonistic action. Thc dcr;rcc and dltratioll of block by d-tubocllrarine 7f'ere not affected significantly by simllltalleolls admi1listratiol1 of diazepam in human beings. It is, therefore, concluded that diazepam ill clillical dost's call be safely used 7('ith d-tllbocllrarille in hlllllmls.