Thousands of mainly Syrian refugees are arriving at Roszke, on the Serbia-Hungary border.
They are physically and psychologically very fragile after a harsh journey by sea and road across several countries, says the international medical organisation Doctors Without Borders (MSF).
Some 2,000 people are crossing over this border daily.
"The needs in Roszke are enormous. This is the first place they arrive after having been on the road for weeks since setting off from Greece,” explains Teresa Sancristoval, project manager for MSF's Emergency Unit in Roszke.
“They can stay here for up to a few days so they need information, food, water, latrines, showers and protection from the cold as temperatures can drop to three degrees at night.
With the heavy rains that we are facing now, the conditions are worsening. We have to be ready as we foresee that this situation will continue for a while."
MSF teams have set up a mobile clinic and have cared for 400 people in four days. Most of the patients (60%) are children with respiratory problems, followed by women (30%) many of them pregnant, and men with infected wounds from the long walks and from jumping fences.
According to medical staff, the exhausting journey has lowered their immune system and those suffering from chronic diseases have had no access to their medication.
Negotiations are ongoing with the Hungarian government to expand the activities and improve the quality of the services offered to the refugees and migrants crossing the border.
Find out more about MSF's work in Serbia