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The Moderate Resolution Imaging Spectrora-diometer (MODIS) onboard EOS Terra measures global aerosol optical depth and optical properties since 2000. MODIS aerosol products are freely available and are being used for numerous studies. In this paper, we present a comparison of aerosol optical depth (AOD) retrieved from MODIS with Aerosol Robotic Network (AERONET) data for the year 2004 over Kanpur, an industrial city lying in the Ganga Basin in the northern part of India. AOD retrieved from MODIS (tau(a MODIS)) at 0.55 mu m wavelength has been compared with the AERONET derived AOD (tau(aAERONET)), within an optimum space-time window. Although the correlation between T alpha(MODIS) and tau a(AERONET) during the post-monsoon and winter seasons (R-2 similar to 0.71) is almost equal to that during the pre-monsoon and monsoon seasons (R-2 similar to 0.72), MODIS is found to overestimate AOD during the pre-monsoon and monsoon period (characterized by severe dust loading) and underestimate during the post-monsoon and winter seasons. The absolute difference between tau a(MODIS) and tau a(AERONET) is found to be low (0.12 +/- 0.11) during the non-dust loading season and much higher (0.4 +/- 0.2) during dust-loading seasons. The absolute error in tau a(MODIs) is found to be about similar to 25% of the absolute values of tau a(MODIS). Our comparison shows the importance of modifying the existing MODIS algorithm during the dustloading seasons, especially in the Ganga Basin in northern part of India.