The crystal and molecular structures of three sydnone derivatives are reported. The compound 3-cyclohexylsydaone crystallizes in space group C2/c of the monoclinic system with sixteen molecules in a cell ofdimensions a = 19.326 (3), b = 9.471 (2), c == 20.005 (4) A,,8 = 106.85 (1)°. The structure has been refined to a final value ofO.05S1 for the conventional R-factor based on 2222 independent observed intensities. Form I of3-(3-pyridyl)sydnone crystallizes in space group P2/n of the monoclinic system with eight molecules in a cell of dimensions a = 7.317(2),1> = 9.283 (2),c = 20.891 (6)A,{3 = 99.61(2)°. The structure has been refined to a final value of 0.0514 for the conventional Rfactor based on 1208 independent observed intensities. Form II of 3-(3-pyridyl)sydnone crystallizes in space group PNc of the monoclinic system with eight molecules in a cell of dimensions a = 9.073 (2), b == 22.267 (5). c == 7.494 (2) A,,8 = 112.15 (2)°. The structure has been refined to a final value of 0.0462 for the conventional R-factor based on 1330 independent observed intensities. Each of the three structures contains two crystallographically independent molecules in the cell. In [he case of3-