The six advisers working in the Department of the Taoiseach are costing a total of €974,122 in salaries, Mr Ahern told the House.
He said he had one special adviser, a programme manager and four others, adding that there had been no increase in the number since the Government took office.
"Under the direction of the programme manager, the primary function of the advisers is to monitor, facilitate and help secure the achievement of Government objectives and to ensure effective co-ordination in the implementation of the programme for government," the Taoiseach said.
"They are also tasked with giving me advice and keeping me informed on a wide range of issues, including business, financial, economic, political, administrative and media matters and performing such other functions as may be directed by me from time to time."
Mr Ahern said that each of the advisers liaised with a number of departments and acted as a point of contact in his office for Ministers and their advisers. They attended meetings of Cabinet committees and cross-departmental teams relevant to their responsibilities.
They also liaised, on his behalf, with organisations and interest groups outside of Government.
In addition, a number of his advisers had specific responsibilities in speech-drafting, he added. His programme manager met other ministerial advisers on a weekly basis. He monitored and reported to him on progress in implementing the programme for government.
Enda Kenny said it seemed strange that none of his political advisers had brought up the matter of former minister of State Ivor Callely being removed from office.
"Good, sound political advice might have led the Taoiseach in a different direction," the Fine Gael leader said.
"I am not privy, of course, to conversations the Taoiseach might have had with these people who cost a half-million euro, but he could have gone to any street in his constituency and got very clear advice for nothing as to when, how and where he might find a successor."
When Bernard Durkan (FG, Kildare North) remarked that the total cost in salaries came to €1 million and suggested that they must give good advice, Mr Ahern said he was satisfied with their work.
"Between them, they cover the entire range of departments, with three or four each. They liaise with Ministers and Ministers of State as well as groups inside and outside the various departments. This involves a range of meetings, and I am satisfied with the work they do," the Taoiseach said.
Labour leader Pat Rabbitte said he agreed with Mr Kenny about "the helpfulness of the Taoiseach's political advisers". They must have been on holiday over the past few weeks, or the Taoiseach had slipped off the leash, because he was not as sure-footed as he used to be.
Pressed further by Mr Rabbitte, the Taoiseach said there was no overlap between advisers and constituency office staff.
"Practically all the people in my constituency office, with the possible exception of one junior person, are civil servants."
Green Party leader Trevor Sargent suggested that there should be specific and published guidelines for the work of special advisers.
Joe Higgins (Socialist Party, Dublin West) said: "It appears that an Arabian sheikh would hardly have such a large retinue as the Taoiseach now has advising him at every turn."
