Polyimides have been prepared from a variety of dianhydrides and isomeric diamines, and their structure-property relationship has been studied. Aromatic and aliphatic dianhydrides were reacted with constitutional and stereo isomers of phenylenediamine and diaminocyclohexane. Solubility behavior, optical transparency, and thermal properties of the obtained polyimides were investigated and the effect of their chemical structure on the properties was studied. Polyimides based on 1,2 diamines showed higher solubility and higher optical transparency than those of 1,4 diamine-containing polyimides. This is probably attributed to more irregularly bent structures of 1,2 diamine-based polyimides. The bent structure would result in less close chain packing, and consequently, weaker intermolecular interactions between polyimide chains. In the cases of aliphatic diamine-based polyimides, optical transparency increased and glass transition temperature decreased in the order of trans, cis, and trans-cis mixture. This is also attributable to decrease in the degree of close chain packing in the same order.