Fanconi anaemia (FA) is a rare genetic disease whose patientshave a high predisposition to haematological abnormalities andcancer. Fas expression levels in peripheral blood lymphocytes samples of73 FA patients were measured to verify if alterations in Fas expressioncould lead to predisposition/resistance to spontaneous or PHA inducedapoptosis, as well as, to reflect some haematological features of thisdisease. The anti- and pro-apoptotic proteins Bcl-2 and Bax were alsoevaluated. FA patients samples could be divided into three differentgroups based on Fas expression: 20 samples had low, 32 normal and 21increased Fas levels when compared to 41 control samples. No correlationwas found between Fas and Bcl-2 expression but a good associationwas obtained with Bax, in the subgroup with increased Fasexpression. The best correlation was seen between Bax expression andapoptosis. Out of the 15 samples with high Bax expression, 11 underwentapoptosis whereas only one out of seven samples with low levels ofBax displayed increased induced apoptosis. Most patients with normalhaematological features expressed Fas within normal levels. It is difficultto establish, however, if Fas-expression is involved in the cause or is aconsequence of the effects observed.