Roche said that the reason for the visit to its sales offices in the eastern city of Hangzhou on May 21 remained unclear.
"We will collaborate fully with authorities for any inquiries," the world-leader in cancer drugs said in a statement, adding that its main sites in Beijing and Shanghai, had not received similar visits.
The Hangzhou visit was carried out by a local unit of China's State Administration for Industry and Commerce (SAIC), a regulator that often probes corruption cases.
Last week, authorities in the country accused top GlaxoSmithKline executives of bribery and corruption, following a 10-month probe into the embattled British drugmaker.
In addition to GSK, pharmaceutical giants including Germany's Merck, Switzerland's Novartis and US-based Baxter have been involved in a far-reaching pricing probe, while France's Sanofi is also being investigated over allegations that it bribed more than 500 doctors.
China's healthcare sector is widely considered to be riddled with graft, given the opaque tendering system for drugs and doctors' low salaries.