Argentine President Cristina Fernandez de Kirchner never had cancer despite having been diagnosed with the disease, her spokesman said.
Mrs Kirchner had her thyroid gland removed on Jan 4 and is currently recovering at home in the south of the country. The government announced just after Christmas that the recently re-elected leader had thyroid cancer.
The operation to remove the gland went well, but when the gland was analysed it turned out to have never contained cancerous cells, said spokesman Alfredo Scoccimaro.
"The original diagnosis has been modified," he told a news conference. "The presence of cancer cells was discarded."
The president is expected to return to work late this month. With the new diagnosis, Mrs Kirchner's medical team "considers that the surgical treatment undertaken is sufficient and the administration of radioactive iodine is no longer necessary," said Mr Scoccimaro.
Several hundred supporters had been camped out near the hospital where she was treated, carrying banners that said, "Strength Cristina."
The president, who won re-election with 54 percent of the vote in October, is popular among Argentines who agree with her generous welfare spending.