Objective assessment of autonomic dysfunction in familial dysautonomia (FD) is largely based on the analysis of cardiovascular responses to challenge maneuvers such as orthostatic stress. Infrared pupillometry (IPM) provides an additional reliable method for cranial autonomic evaluation and has the advantage of requiring minimal cooperation.This study was performed to determine whether IPM contributes to the assessment of autonomic function in FD patients. In 14 FD patients and 14 healthy controls, we studied absolute and relative light reflex amplitude, pupillary constriction velocity (v(constr)), pupillary diameter, early and late pupillary re-dilatation velocity (v(dil 1), v(dil 2)) after dark adaptation. Prior to IPM, all patients had an ophthamological examination to evaluate refraction and corneal integrity. In comparison to controls, patients had a significant reduction of the parameters reflecting parasympathetic pupillary function (absolute light reflex amplitude 1.34 +/- 0.21 vs. l.86 +/- 0.14 mm, relative light reflex amplitude 22.74 +/- 7.11% vs. 30.76 +/- 3.57%, v(constr) 3.75 +/- 1.09 vs. 5.80 +/- 0.59 mm/s) and of the parameters reflecting sympathetic pupillary function (diameter 5.69 +/- 0.66 vs. 6.35 +/- 0.60 mm, v(dil 1) 1.29 +/- 0.23 vs. 1.95 +/- 0.23 mm/s, v(dil 2) 0.64 +/- 0.13 vs. 0.72 +/- 0.l2 mm/s; Mann-Whitney U-test: p<0.05). The non-invasive technique of IPM demonstrates dysfunction not only of the cranial parasympathetic, but also of the cranial sympathetic nervous system and, thus, further characterizes autonomic dysfunction in FD.