Interferon-gamma (IFN-gamma) mediates the final damage of the stem cell compartment in Aplastic Anaemia (AA). Normal subjects homozygous for 12 (CA) repeats of polymorphism variable number of dinucleotide (CA) repeat (VNDR) in position 1349 of the IFN-gamma gene (IFNG) were shown to overproduce IFN-gammain vitro. We studied the distribution of polymorphism VNDR 1349 of IFNG in 67 Caucasian AA patients and in normal controls. Genotype (CA)12-12, (homozygosis for allele 2) and the single allele 12 were significantly more frequent (P = 0.005 and 0.004 respectively) in patients versus controls. The polymorphism was equally distributed in AA patients regardless of their response to immunosuppression. Homozygosity for 12 (CA) repeats of polymorphism VNDR 1349 of IFNG is strongly associated with the risk of AA in Caucasian subjects.