馬偕博士抵達淡水之後，就在所租的住寓提供人診療、供應西藥、開刀、拔牙和住院等服務。尤其當時民眾廣為瘧疾所苦，馬偕的奎寧水(quinine)是特效藥而大受歡迎，因此求診者與日俱增。因此，1873年5月，馬偕另租民房做為診所，名為「滬尾醫館」。後來，馬偕得到一位同姓馬偕的美國婦人捐款，他就用這筆錢蓋了一棟建築形式中西合壁的醫院（外觀是閩南風格的平房，但窗戶卻是西式的圓拱窗），1879年9月14日正式成立「滬尾偕醫館」（現今馬偕醫院的前身），是北臺灣第一所西醫院。到1894年，每年受診者己逾一萬人次。

From the time Dr. MacKay arrived in Tamsui, he offered medical treatments, western medicine, surgeries, tooth extractions and hospitalization services at his own rental residence. The general public was suffering from malaria at that time and MacKay’s quinine was very efficient and widely welcomed, which led more and more people to his clinic for treatments. Therefore, in May 1873, MacKay rented another residential building and turned it into a clinic, named “MacKay’s Clinic.” Later, he received a donation from an American woman, whose last name was also MacKay, and used this donation to build a hospital combining both eastern and western styles, with a Minnan style flat house and western arched windows. On September 14, 1879, he officially established the MacKay Clinic, which later became MacKay Hospital. It was the first western hospital in northern Taiwan. By 1894, the total number of patients reached ten thousand annually.