We compared the cross-polymerization of diacetylene units, incorporated in different ways into polyamide (PA) matrices: as fragments of the PA main chains (PA1) and as pendant groups of the PA main chains (PA2). At room temperature the reaction proceeds only in PA1 via 1,4-addition (cross-links I). However at high temperature besides of cross-links I another type of cross-links (cross-links II) is formed, presumably via 1,2-addition reaction. In PA2 only cross-links of type II are formed at high temperatures.