Liquid crystalline polymers containing specified ratios of repeat units derived from hydroquinone, 2,6-naphthalenedicarboxylic acid, 4-hydroxybenzoic acid and optionally terephthalic acid have exceptionally high heat distortion temperatures, making especially useful for service at high temperatures. Compositions containing reinforcing agents, especially fibrous or platy reinforcing agents are particularly useful. These polymers and compositions are useful for electrical and electronic connectors, and as films for the electronics industry, and for other uses.