[en] Trace amounts of hafnium in zirconium standard samples (JAERI-Z15,-Z16) were determined by neutron activation and gamma-ray spectrometry where 214.3 keV gamma-ray emitted from sup(179m)Hf (T sub(1/2) = 18.6 sec) are counted by a Ge(Li) detector. The zirconium samples and hafnium standards were irradiated in a pneumatic tube (phi sub(th) = 4.6 x 10¹³ n/cm².sec) of JRR-4 for 10 sec independently. After irradiation the samples and standards were transferred to the Ge(Li) detector and cooled for 40 sec. The gamma-ray spectra were observed with 100 sec counting. Analytical results of zirconium standard samples were as follows; JAERI-Z15 1.8 +- 0.11 ppm (n = 12), JAERI-Z16 41 +- 1.9 ppm (n = 12). On the assumption that the peak detection limit is three times larger than the standard deviation of background counts, the detection limit for hafnium was 0.0012 μg. The detection limit of hafnium content was 0.04 ppm for 30 mg of the sample. (author)