The Olivarez General Hospital started as a clinic at Dr. Rosario Olivarez's residence in San Dionisio, Parañaque in 1958. After her patients slowly started to increase, Dr. Rosario started a maternity clinic with fifteen beds. Her patients continued to increase until her whole house was fully occupied. In 1960, after the house was no longer capable of accepting more patients, Dr. Pablo Olivarez, Dr. Rosario's husband, sought to create a hospital for his wife. He began the initial planning of Olivarez General Hospital on that same year, however, due to insufficient funds, he started the construction a decade later.
In July 1974, Dr. Pablo Olivarez finished the construction of the two-storey building but it took about a year before they formally opened the OGH. They started with 120 beds but this sum dwindleded down to 50 due to internal problems beyond their control. Some doctors left OGH to form their own hospital.
On December 1992, Dr. Imelda Olivarez-Orteza, the eldest daughter of Drs. Pablo and Rosario Olivarez, together with her husband, Dr. Ephraim Neal C. Orteza came back from the US after working for a few years as Pediatric Consultants in West Virginia. They finished their residency training in General Pediatrics at the Lincoln Hospital of the New York Medical College. The ownership of OGH was transferred to them and they took over the hospital administration on January 1993. Dr. Ephraim Neal C. Orteza took up his Master's degree in Hospital Administration at the Ateneo de Manila University and he graduated in 1995.
Under their management, OGH was transformed into one of Parañaque City's best private hospitals. They have renovated the old building thrice - first in 2004, second in 2013 where a third floor was added, and third in 2016 where a new Medical Arts Building was constructed. More services were also made available - a CT Scan, a Physical Therapy Department, an ICU, a Hemodialysis Unit, a High Risk Pregnancy Unit, an Ultrasound unit with 2D-Echo for adults and children, an Endoscopy Unit, and a NICU. The OR Complex was also expanded. In 2018, OGH opened its new Medical Arts Building, which houses all the doctors' offices and a cafeteria for both patients, visitors, and doctors. In the near future, OGH aims to start the renovation of the ground floor of the main building.
Through the years, Olivarez General Hospital has slowly grown from a maternity lying-in clinic to a fast growing hospital, serving the health care needs of its surrounding communities and nearby cities.