Party sources said the 68-year-old leader's checkup was due for two months and was delayed because of the Bihar Assembly polls.
Congress president Sonia Gandhi has gone to the US for a medical check-up in the middle of the Winter Session of Parliament, which began last week.
"She has gone to the US for a regular, routine checkup. She will return after a week," Congress spokesperson Randeep Surjewala said in Delhi.
Party sources said the 68-year-old leader's checkup was due for two months and was delayed because of the Bihar Assembly polls.
Speculation over the Congress president's health peaked in 2011, when she left India for a surgery in the US. Neither her family nor the ruling party disclosed anything about her condition at the time.