Yes, according to this analysis by The Heritage Foundation.

On October 23rd, a reporter asked Speaker Nancy Pelosi (D-CA): ?Madam Speaker, where specifically does the Constitution grant Congress the authority to enact an individual health insurance mandate?? Speaker Pelosi shook her head and before moving on to another question replied: ?Are you serious? Are you serious??? Pressed for a more substantive response later, Pelosi?s press spokesman admonished the reporter: ?You can put this on the record. That is not a serious question. That is not a serious question.?
The Congressional Budget Office (CBO) disagrees. In 1994, the CBO said of an individual mandate to buy health insurance:

A mandate requiring all individuals to purchase health insurance would be an unprecedented form of federal action. The government has never required people to buy any good or service as a condition of lawful residence in the United States. An individual mandate would have two features that, in combination, would make it unique. First, it would impose a duty on individuals as members of society. Second, it would require people to purchase a specific service that would be heavily regulated by the federal government.

……Yesterday The Heritage Foundation?s Center for Legal and Judicial Studies released a Legal Memorandum written in conjunction with Georgetown University Law Center Professor Randy Barnett and Nathaniel Stewart explaining: Why the Personal Mandate to Buy Health Insurance Is Unprecedented and Unconstitutional.