Napa County Sheriff's Capt. Tracey Stuart says deputies were dispatched to the San Francisco Democrat's home outside St. Helena on Monday after receiving an alert from the alarm company.
They found glass broken on the front door and a pool house door but no suspects. No one was home at the time.
Stuart says it wasn't immediately clear whether anything was stolen. Some of the obvious valuables were still there.
Pelosi also owns a home in San Francisco.