Whiskers of poly (4-hydroxybenzoate) [poly(4-HBA)] were prepared by polycondensation of free 4-hydroxybenzoic acid with acetic anhydride and pyridine in a high boiling inert solvent. The purity of the monomer is decisive for the success of the synthesis. For a less pure 4-hydroxybenzoic acid, the preparation of acetylated oligomers with acetylchloride, followed by polycondensation of the isolated oligomers is a suitable alternative. Whiskers, with a solid-solid phase transition at 364-degrees-C were obtained, which is the highest temperature reported for this transition so far. Two batches of composites were prepared from nylon-6 using polyester whiskers with an alkaline or an acidic surface treatment. A third batch was prepared using poly(ester-amide) whiskers. The mechanical properties of these composites indicate that the surface treatment does not play any role, and that the poly (ester-amide)s are inferior to the polyester whiskers, because they are not single crystals.