Constitution

Constitution is one of the six character abilities. It determines the chance that a character can be resurrected from death by magic and it's adds a bonus to hitpoints for the first 9 nine levels for all warrior classes and the first 10 levels of all other class groups. For example, if a character's constitution is permanently boosted by one point and the character is lvl 11 warrior, hit points for previous levels are added retroactively.

Warrior classes gain from 17 a higher hitpoints modifier than any other class group. This character ability is essenstial for all classes, but more so for fighters, paladins, rangers and barbarians. Paladins and rangers have a high minimal requirement for constitution.

Characters with more than 20 or a higher constitution, will also regenerate lost hitpoints during and outside of battles. It's not known if this effects is exclusively for warriors or that all class groups can benefit from this.

Permanent constitution boosts

 * Manual of Bodily Health in Baldur's Gate (game) and Baldur's Gate: Enhanced Edition
 * In Baldur's Gate II: Shadows of Amn, a constitution boost is gained from offering a Tear of Bhaal in Hell.
 * Machine of Lum the Mad in Baldur's Gate II: Throne of Bhaal

Temporary constitution altering items

 * Girdle of Fortitude
 * Potion of Fortitude