Abstract An “absolute”asymmetric synthesis of chiral dimers and polymers has been accomplished through a process of crystallisation of an achiral monomer in a chiral crystal, followed by a topochemical photopolymerisation. Once (2π+2π) photocycloadditon had been selected as a suitable reaction, we designed the chiral crystalline motifs needed for a reaction with quantitative enantiomeric yield. Unsymmetrically disubstituted dienes, translationally related in a chiral crystal, and where reaction occurs between non-equivalent double bonds, separated by 4.0a, fit the suggested model best. The execution of the synthesis involved the following steps. By applying some empirical rules of “crystal engineering”, we selected a family of chiral resolved molecules (which guarantee a chiral crystalline motif), among which R(-) or S(+) ethyl-2-cyano-3(p-sec-butyl-3′-E-propenoate)-phenyl-E-propenoate- 1 was found to fulfil all the stated requirements, yielding photodimers and polymers with quantitative diasterioisomeric yield. Finally, on the basis of the crystal structure of 1 we have designed at least two achiral molecules which pack in chiral structural motifs isomorphic with 1 . Irradiation of crystals grown from the melt, led to polymers with high, probably quantitative optical yields. A possible model for an amplification of the generated chirality will be discussed.