Abstract: Preparation and characterization of multi-wall carbon nanotube(MWCNT) modified glassy carbon electrode(GCE) was described and electrochemical behavior of tyrosine(TRS) at this modified electrode was studied.As shown by experimental results,the oxidation potential of TRS was lowered obviously at the modified electrode,while its oxidative peak current was increased.Linear relationship between values of peak current and concentration of TRS was found to be kept in the range from 3.0×10-6 to 1.0×10-4mol·L-1.Detection limit(S/N=3) of the method found was 1.6×10-7mol·L-1 when the enrichment time of 4 min was taken.As shown by results of test for interferences,the proposed method was proved to have good selectivity.Based on these facts a differential pulse voltammetric method for determination of tyrosine was proposed.In its application to the determination of TRS in human urine samples,values of RSD′s(n=6) obtained were in the range from 3.1% to 4.5%,and values of recovery found were in the range of 93.8%-111.8%.