A new histamine H2-receptor antagonist, ebrotidine (4-bromo-N-[2-({2-[(diaminomethylene)amino]-1,3-thiazol-4-yl}methylthio)ethylaminomethylene]benzenesulfonamide) is triclinic, space group P1̅, with a 10.004(2), b 10.611(2), c 10.846(2) Å, α 96.43(1), β 105.48(2), and γ 116.58(2)°; Z = 2, dc = 1.659; R = 0.031, Rw = 0.034 for 2760 reflections.At. coordinates are given.The main difference between the title compound and other related derivatives is in the torsion angles defining the conformation of the side chain.In the present compound the conformation of the C(thiazole)-C-S-C-C-N side chain is given by torsion angles of 74.5(3), -76.0(3), -91.5(3), 72.2(3) and -89.0(3)°, this being the 1st reported derivative having this conformation.Another difference is seen in the intermol. H-bonding scheme.