On the 1st of January 2012, Switzerland introduced the diagnosis-related group hospital tariff structure (SwissDRG). It was recognised that healthcare provided to the most vulnerable patient groups would be a challenge for the new SwissDRG. Coincident with the implementation of SwissDRG, we explored hospital experts' perceptions of which patient groups are vulnerable under the SwissDRG system, what has changed for this group, as well as solutions to ensure adequate access to health care for them. We interviewed 43 experts from 40 Swiss hospitals. Participating experts named several vulnerable patient groups who share some common characteristics. These hospital experts were concerned about the patient groups that are not financially profitable and questioned the practicability of the current regulation. At the same time, they highlighted the complexity associated with caring for this group under the new SwissDRG and reported measures at the macro, meso, and micro levels to protect vulnerable patient groups from negative effects. To curb negative outcomes for vulnerable patient groups after the introduction of the SwissDRG, the Swiss legislation has introduced various instruments including the acute and transitional care (ATC) measures. We conclude that ATC measures do not produce the expected effect the legislators had hoped for. More health data is needed to identify situations where vulnerable patient groups are more susceptible to inadequate health care access in Switzerland.