The NPAs have always been a big worry for the banks in India. It is just not a problem for the banks; they are bad for the economy too. The money locked up in NPAs is not available for productive use and adverse effect on banks' profitability is there. The Public Sector Banks have shown very good performance over the private sector banks as far as the financial operations are concerned. However the position of Public Sector Banks is not so good in the area of Non-Performing Assets (NPAs) as compared to Private Sector Banks. This paper examines the causes of NPAs and a comparative study is done between Public Sector Banks and Private Sector Banks using mean, standard error, covariance and t-test. The result showed the significant difference between NPAs of Public and Private Sector Banks under study. Keywords: NPA, Gross NPAs, PSBs, Private Banks, Gross Advances