Different modifications of the zeolites Na+-Beta and LTA were applied for improving the working characteristics of a urea biosensor. The bioselective membrane of the biosensor was based on urease and different zeolites co-immobilized with bovine serum albumin on the surface of a pH-FET. It was shown that the biosensors modified with the zeolites H+-Beta30 and H+-Beta50 are characterized by increased sensitivity to urea. The influence of the zeolite concentration on the sensitivity of the biosensors was studied. The optimal concentration of the zeolites H+-Beta30 and H+-Beta50 in the bioselective membrane was 15%. Different variants of co-immobilization of urease and zeolite H+-Beta30 were studied and the optimal method was selected. Thus, a general conclusion is that the urea biosensor sensitivity can be improved using zeolite H+-Beta30 for urease immobilization in the bioselective membrane.