Three patients with Fanconi's anemia were analyzed for chromosome breaks. T and 
B cells were separated and grown in tissue culture with PHA and pokeweed antigen 
to ascertain the rates of breakage in these lymphocytic subpopulations. It has 
been found that there is no statistically significant difference in breakage 
rates in T and B lymphocytes. It is postulated that both T and B cells could be 
involved in the development of leukemia in Fanconi's anemia patients, assuming 
that chromosome breaks constitute a factor predisposing to the development of 
malignancy.