The detective sensitivity vary obviously in the assay of HBV DNA by means of polymerase chain reaction with 18 different sample treatment procedures. Higher sensitivity was found in three methods, namely, guanidine thiocyanate/phenol/chloroform, NaoH denaturation and sodium octanoate. The procedure of phenol/chloroform was too labor-intensive to be accepted in routine clinical testing, sodium octanoate which may suppress the inhibitory effect of denatured albumin on the polymerase chain reaction and thus the sensitivity was higher than the method of NaOH denaturation. Treatment of samples with 30-50 mmol/L of sodium octanoate in final concentration for the detection of HBV DNA has shown to be very sensitive, simple and reproducible.