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Abstract--'T n.m.r. spectra have been measured for thirty-two polychloroalkenes including (i) monosubstituted compounds CH2-=CHCCI,H,-,X, where -X stands for -H, -CI, alkyl, and trisubstituted alkenes CCI,-CHAIk, none of which form geometric isomers; (ii) disubstituted compounds RCH-CHR'; (iii) and (iv) trisubstituted compounds of the types R C C I -CHR' and CHCI-CCIR, respectively. Compounds (ii) to (iv) represent either individual isomers or mixtures of the Z and E forms. In the case of compounds (ii) and (iii), the ordering of chemical shifts is OB > 0 , for the @-carbon atoms and 0, <-: Oa for the adjacent tetrahedral ones. On the contrary, the signals of the sp2-carbon atoms of compounds (iv) obey the rule 6 , < 6,.The effect of vinyl and allyl groups as substituents on the 13C chemical shifts of chlorine-containing groups is discussed. The dependence of the spz-carbon spin-spin coupling constants J(l3C-lH) on the number of chlorinated substituents in the molecule is also considered.