Spontaneous chromosome aberrations (CA) were analyzed in 3 Fanconi's anemia (FA) patients, 8 family members, and 9 healthy individuals. Peripheral blood lymphocytes obtained from each individual were cultured and cytogenetic analysis was performed on standard and sequential G‐banded metaphases. The numbers of abnormal cells and breaks were found to be higher in AF patients compared to the other groups (p< 0.0001). Breakpoint distribution was statistically analyzed considering the formula proposed by BRØGGER (1977), showing a non‐random pattern among FA patients but not among controls or relatives (p< 0.001). Five chromosomal bands located at 1p36, 1p22, 1q21, 3p14, and 3q21 were non‐randomly involved in spontaneous CA in FA patients. These bands were correlated with the chromosomal location of fragile sites, oncogenes, and breakpoints involved in cancer‐rearrangements. A significant correlation with the location of fragile sites (p < 0.03) and breakpoints involved in cancer‐rearrangements (p < 0.001), particularly with AML chromosome anomalies (p < 0.03) was found, suggesting a possible relationship with the high predisposition to cancer observed in this disease.