Atenolol does not present well-known redox response at thebare glassy carbon electrode. Surface modification of the electrodewith PDA thin film allows analyzing the alteration of the poly-mer electrochemical response. Voltammetric studies of atenolol atthe surface of the modified electrode have shown adsorption-likebehavior in which, the atenolol is linked to the composite. Differen-tial pulse voltammetry is applied successfully for the determinationof trace amounts of atenolol in the clinical and pharmaceuticalsolutions by using the inhibitory effect of atenolol on voltammet-ric response of the modified electrode. The results suggested thatthe PDA modification of electrodes may provide a new strategy foratenolol concentration determination in physiological solutions.