The mission hospital at Mergareja was founded in 1906 by the Doopsgezinde Zending (Baptist Mission). Initially it was considered to be an auxiliary hospital, as there was no resident medical doctor. Later on (1914) the doctor Bervoets, who had been employed in the Modjowarno hospital, served the Baptist Mission , a.o. in this hospital. The Koloniaal Verslag 1915, Annex T-XI mentions this hospital as a category 2 hospital (26-75 beds) that received in 1914 f 3,500 subsidy for a European doctor and f 1,920 for nursing personnel. The subsidy for treatment costs was in that year f 2,500. In 1920, the medical doctor H. Bervoets reports the outcome of the years 1918 and 1919: admitted resp. 645 and 837 patients and nursing days resp. 23,079and 25,827 (on average 71 patients). In the Algemeen Handels-blad of 11 september 1920 it is remarked that the population has no appetite to make use of Western medical care. They are adivised by friends and family that they will get an accident when using the medicaments of Mergareja and beg to pass their doors. They are more trustful of the qualities of the scarecrow puppets that may oppose the evil spirits that evoked the disease and are put in front of the house. The Dutch paper NRC of 30 November 1917  reports of 767 patients (161 with malaria and 50 with venereal diseases). In 1916 there were 591 admittances with 24,939 nursing days and 1,127 new outpatients with 15,792 consults.

Mergareja (Mergorejo) was situated in the Residency Japara-Rembang, in the Regency of Pati, Province of Central Java. It was a subdistrict of the District Pati. The Regency Pati had 512,000 inhabitants, of whom 462 Europeans and 5,600 Chinese. The town of Pati had 22,000 inhabitants,of whom 200 Europeans and 2,300 Chinese. The main river is the Juwana. The Regency is very fertile. Near the coast are fish ponds. Sugar and rice fields are characteristic for the landscape (Gonggryp 1934, 1153).