Jay Kay Foon-lok, a specialist in cardiology from Hong Kong, has recently been busy travelling between the special administrative region and Guangzhou to treat his patients.

"It's, indeed, energy-sapping," he says. "I do four to seven surgeries in Hong Kong a week but my colleagues and I are in our 40s and are full of energy."

Kay's busy life has been made possible thanks to the Closer Economic Partnership Arrangement between the mainland and Hong Kong, which has opened up a huge market for Hong Kong's medical service providers. Such companies are now allowed to set up wholly owned outpatient clinics in Guangdong under Supplement V of the CEPA, which came into effect on Jan 1, 2009.

As of Jan 1, 2011, they have been able to set up wholly owned hospitals in Shanghai, Chongqing and the provinces of Guangdong, Fujian and Hainan. Another amendment to the arrangement, which became effective this year on April 1, means Hong Kong's medical services providers can now set up wholly owned hospitals in all municipalities directly under the control of the central government and the provincial capitals.

"If we count just 1 percent of the population in Guangdong as the high-end market who want personalized, high-end medical services, we are already talking about a huge potential," Kay says. "As the country becomes richer, the number of such people will become bigger."

Guangdong has more than 105 million inhabitants, according to the Guangdong Statistics Bureau. Now, thanks to the CEPA, that vast population of all medical services from nearby Hong Kong and organizations such as Kay's.

His 200-square-meter Hong Kong Wan Zhi Medical Services Center, which is located in a 200-sq-m space in a prestigious office building in Guangzhou, the capital of Guangdong, opened in April 2011. Seven of its eight doctors are from Hong Kong.

Kay says 40 percent of patients are mainlanders while 30 percent are from Hong Kong and 30 perent are foreign nationals.

He has not found it difficult to adjust to working in the mainland. As a director of Po Leung Kuk, Hong Kong's leading social service organization and fundraiser, and as someone involved with charitable organizations, he has been attending various programs on the mainland for the past nine years.

"We started our consultations and preparations in 2008, after we heard that the mainland market may open up," he says.

Kay and his partners have invested $2 million in the Guangzhou clinic. He says it will only be possible to judge the profitability of the venture after a four-year cycle.

"It all depends on whether our services are being recognized and well accepted," he says.

"I am happy that we are seeing repeat visitors and I am optimistic about the outlook."

It is a sector that is getting a lot of interest from organizations outside of the mainland.

The Guangdong Health Department had issued permits to 19 wholly owned clinics backed by Hong Kong and Macao investors by the end of June and are processing the applications for four more wholly owned clinics and one wholly owned hospital, according to the department.

liwenfang@chinadaily.com.cn