(BBC NEWS) Islamabad – The prime minister, who faces jail and being barred from office if convicted, pleaded not guilty.
Mr Gilani argues that the president, who denies the corruption charges, has immunity as head of state.
President Zardari is accused of using Swiss bank accounts to launder bribes.
The Supreme Court has said Mr Gilani defied a court order to write to the Swiss authorities and ask them to re-open the cases against Mr Zardari.