The ministry said 34,071 people over the age of 65 died during the period of July 16 to Aug. 15, the height of the heat wave. That's 4,175 more than the same time last year.
Officials from the ministry's Superior Health Institute, which compiled the figures, said more study was needed to determine if the deaths could be blamed entirely on the heat. But they stressed that the weather clearly played a role.
"There is a relationship between heat peaks and mortality," said Dr. Donato Greco, an official with the institute.
The heat may have directly caused some deaths or worsened existing illnesses and conditions, officials said.
Health Minister Girolamo Sirchia said the number of elderly deaths was as high as expected considering the number who died in other European countries.
France topped the list, with the government saying an estimated 11,435 people died because of the heat. The country's leading undertaker put the number at 15,000 on Tuesday.
The Italian Health Ministry had initially refused to release data on deaths during the heat wave, saying it was impossible to determine if weather was the cause. But it changed course after a public outcry erupted after France released its startling figures.
In Italy, which has a population of 57 million, temperatures started rising in June and soared well into the 100s, with high humidity in July and August in many parts of the country.
The ministry launched an investigation late last month, following media reports that the death rate rose dramatically during the first half of August, particularly among the elderly, the ill and people living alone.
Calls placed by The Associated Press to several Italian municipalities in the second half of August showed a significant increase in the numbers of deaths compared with the same time last year, although officials said the causes weren't certain.
In France, the death toll sparked a political uproar over who was to blame, with calls for the health minister to resign. The center-right government issued a report this week blaming the deaths on hospital understaffing during summer holidays, widespread failure among agencies and health services to coordinate efforts, and chronically insufficient care for the elderly.
In Paris on Thursday, France's embattled health minister, Jean-Francois Mattei, defended his response to the heat wave, and said he agreed with the report's finding that a special health alert system should be established to prevent another disaster.
No other European country came close to France's death toll.
Spain has reported 100 heat-related deaths, while Portugal, which has seen the harshest and longest heat wave in living memory, scrapped its initial estimate of 1,300 deaths and lowered it to just four.
In Amsterdam, Dutch authorities estimated 1,000 to 1,400 victims.
In Britain, there were 907 more deaths registered during the week ending Aug. 15 compared to the average from the same period over the previous five years, officials said. The Department of Health said it was "fair to assume" that some deaths resulted from high temperatures, but stressed there was no way of knowing if heat caused the spike.
German authorities, who tallied each case rather than estimate them, have reported about 40 heat-related deaths this summer, but several cities recorded significantly more deaths than usual.
In Belgium — where the Royal Meteorological Society reported the hottest summer since it began recording temperatures in 1833 — the Health Ministry is working on an overall survey, expected to be ready by the end of the month. But initial reports from hospitals indicate 150 more deaths between July 1 and Aug. 15 than the same period last year, the ministry said.
In Serbia-Montenegro, three people were believed to have died from the heat wave in the Montenegrin capital, Podgorica.
Other European countries, including Austria, Bulgaria, the Czech Republic, Hungary and Slovakia, reported no deaths directly related to the heat.
By Alessandra Rizzo