The tape, which aired on Wednesday, was made on 31 May, the station said.
One of the three men, shown eating at a table and then seated next to the others, said they were being treated well. The man was speaking in Italian.
The three, dressed in short-sleeved shirts and trousers, appeared to be in good health.
"Today is Monday, May 31 2004. We tell the government, the Pope, the Catholic church and our families that we have been treated in an excellent manner up to now and we are well," the channel quoted one of the Italians as saying as he pointed to his colleagues.
"We have had no problems with the men holding us in this place," he said as he sat between the other two in front of a white wall.
Four Italians working for a US security firm were seized on 12 April near Baghdad. One of them was shot dead after Italy refused to bow to demands to withdraw its troops from Iraq.
Italy has some 2700 troops based in the southern town of Nasiriya.
Aljazeera also showed an Arabic-language statement by their captors, calling itself the Green Battalion, urging Italian people to demonstrate against the policies of US President George Bush and Italian Prime Minister Silvio Berlusconi.