Phyathai 2 Hospital expects a spike in foreign patient numbers once the Asean Economic Community (AEC) kicks off in 2016.
Executive director Anantasak Apairatana said the hospital's 100 foreign patients a day account for between 5% and 6.67% of the hospital's daily total of 1,500 to 2,000 patients.
Overall patient numbers have been increasing by 10% annually, he said.
Phyathai 2, part of Bangkok Dusit Medical Services Plc (BGH), started focusing more heavily on foreign patients a decade ago.
In 2010, the Health Network Group controlled by Wichai Thongtang sold the Phyathai and Paolo Memorial hospital chains to BGH, now the second-largest hospital group in Asia-Pacific, for 12.6 billion baht.
Dr Anantasak said Phyathai 2 Hospital has the largest base of foreign patients among the six hospitals under the two chains.
Most of the foreign patients are from Southeast Asian countries, particularly Laos, Myanmar, Cambodia and Vietnam, while others come from the Middle East and even Bhutan.
"We're constantly recruiting new employees in line with the increase in new patient numbers. Most hospitals here have problems communicating in English, so we're increasing our number of translators as well as Filipina nurses who are fluent in English," said Dr Anantasak.
The hospital currently has five Filipina nurses and 15 full-time translators including from Vietnam and Bangladesh.
Dr Anantasak expects the ratio of foreign patients to increase to 20% of total patients by 2015, with plans to expand its customer base to include new markets such as China, India and Bangladesh along with as-yet untapped Middle East countries.
The hospital has 380 beds now and expects to reach its full capacity of 500 beds within 3-5 years, he said.
Some 300 million baht is being spent this year on new centres including a one-stop health check-up clinic that opened at the start of this year.
The third quarter will see the addition of a brain centre, a hybrid operating room and a bone and joint centre.
A hybrid operating room is a surgical theatre that is equipped with advanced medical imaging devices such as fixed X-ray image intensifiers, CT scanners or MRI scanners, imaging devices that enable minimally invasive surgery.
Phyathai 2 Hospital yesterday announced the opening of its 100-million-baht gastrointestinal and liver centre.
"Gastrointestinal disorders are common in Thailand and other Asean countries, as we all eat spicy food," said Dr Anantasak.