Summary: The variable heavy chain region (VH) genes of 3 untreated patients with B cell chronic lymphocytic leukemia (B CLL) were cloned and analyzed. The VH family used was VH3 11, VH3 72 and VH3 33. More than 2 % difference from the corresponding germline gene was detected in all the 3 obtained potential functional genes (average 16.7). Mutation pattern analysis indicated evidence of antigen selective pressure observed in 1 of 3 cases. Our findings suggested that the tumor cells originate from post GC cells. The VH family used was VH3 11, VH3 72 and VH3 33. More than 2% difference from (B CLL) were cloned and analyzed. The corresponding germline gene was detected in all the 3 obtained potential functional genes (average 16.7). Mutation pattern analysis indicated evidence of antigen selective pressure observed in 1 of 3 cases. Our findings suggested that the tumor cells originate from post GC cells.