A potentiometric carbon paste sensor was fabricated for determination of clarithromycin based on incorporation of the ion association complex of the clarithromycin-phosphotungstate. The proposed sensor exhibited a Nernstian slope of 59.2±0.3 mV per decade for clarithromycin over a wide concentration range of 7.4×10⁻⁷ to 1.5×10⁻³ M, with a low detection limit of 5.0×10⁻⁷ M. The proposed sensor manifested advantages of very fast response, long life time and, most importantly, excellent selectivity for clarithromycin relative to a wide variety of common foreign inorganic cation, and also biological species. The sensor was successfully applied to determine clarithromycin in clarithromycin tablet, blood serum and urine samples. The inclusion complex formation between β-cyclodextrin and clarithromycin was studied by the proposed sensor. The influence of the temperature on the response of the sensor was investigated and the temperature coefficient of the sensor was calculated.