A new monomer (7) was prepared by alkylation of N,N,-bis(4-hydroxyphenyl)biphenyl-3,3',4,4'-tetracarboxylic imide with 11-bromoundecanol. This imide diol (7) did not form a LC-phase, but showed two reversible first-order transitions in the solid state. It was polycondensed with various aliphatic dicarboxylic acid dichlorides in 1-chloronaphthalene. The phases and phase transitions of the resulting poly(ester-imide)s were characterized by optical microscopy, DSC measurements and X-ray measurements at variable temperature. All poly(ester-imide)s formed a crystalline smectic phase in the solid state. In the case of short spacers enantiotropic smectic-A phase were observed which vanished in the case of long spacers.