Melting behavior was studied for 6-10 polyamide prepared by interfacial polycondensation, developed by Morgan et. al. in 1963, in order to clarify the resultant texture. In the interfacial filmforming procedure without pulling up the resultant film, the average molecular weight close to the weight average molecular weight decreased with the polymerization time, which reflects the production of low molecular weight fractions as the polycondensation proceeds. This also reflected the depression in the melting peak in the DSC thermograms. On the conditions under the winding-up of the film and stirring in the original system, much more yields and high molecular weight materials were obtained, which was already pointed out by Morgan et. al. The measurement of DSC thermograms of the samples obtained showed that the crystallinity of the polymer was almost 30% for the as-polymerized samples, irrespective of the preparation methods and increased on annealing up to 50% at the most due to the crystallization of uncrystallized portion upon polymerization. The similarity in the melting behavior among the samples polymerized under different conditions and to their melt-quenched samples suggest that crystallization during polymerization took place under high super-coolings in the interface.