A novel chemically modified electrode was constructed based on multiwalled carbon nanotubes, MCM48 molecular sieve composite modified glassy carbon electrode .The modified electrode showed that it can be used for simultaneous determination of acetaminophen (ACT) and codeine (COD), simultaneously. The measurements were carried out by the application of differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA) methods. The fabricated sensor revealed some advantages such as excellent selectivity, good stability and high sensitivity toward ACT and COD determination. Application of DPV method under the optimum conditions showed the modified electrode provides linear responses versus ACT concentrations in the range of 0.2-40 μM and 80-350 μM. The results for COD showed the linear responses in the ranges of 4-70 μM and 150-400 μM respectively using DPV method. The modified electrode was used for determination of ACT and COD in real samples like human blood serum and plasma with satisfactory results.