OBJECTIVE A method of first derivative UV spectrophotometry for growth hormone in PLGA microspheres was described. METHOD The first derivative UV spectrophotometry for growth hormone was established at 306 nm and 282 nm. RESULT The recoveries of high,medium and low concentrations of growth hormone were 98.16% ,99. 18% and 96.10% respectively with RSD 0.99%, 1.50% and 4.03%(m =5). The encapsulation efficiencies of microspheres was 87. 13% with RSD 0.91 % (n = 5).CONCLUSION The assay for growth hormone in PLGA microspheres is simple,rapid and reliable.