The determination of selenium in amino acids in the range 1.0 to 0.1 ppm is of significance for biomedical investigations. This work makes use of the improvement of sensitivity in neutron activation producing the 77mSe nuclide when the sample is activated by reactor pulses. Neutron pulses of an integrated energy averaging 13 MW sec from a TRIGA Mark II reactor were used. Actual biological samples were simulated adding ppm amounts of sodium selenite to 1-g amounts oj glycine. Results are reported that show a percentage standard deviation of mean value of ± 1.3%.