Background: Healthcare personnel are responsible for providing patient-centered care regardless of their patients' language skills, but language barriers is identified as the main hindrances providing effective, equitable and safe care to patients with limited proficiency in a country's majority language. This study is a national multisite cross-sectional survey aiming to investigate communication over language barriers in pediatric oncology care. Material and Methods: A survey using the Communication over Language Barriers questionnaire (CoLB-q) distributed to medical doctors, registered nurses and nursing assistants at six pediatric oncology centers in Sweden (response rate 90%) using descriptive statistical analyses. Results: Professional interpreters on site were the most common solution when using an interpreter, although relatives or even children were used. The use of professional interpreters on site differed among the professions and in different clinical situations, such as medical encounter, education or procedure preparation. All professions reported that the use of professional interpreters greatly increased care relationships, patient safety and patient involvement in care. Conclusions: Healthcare personnel seem to believe that professional interpreters are crucial when caring for patients and family members who do not speak the majority language, but there is an obvious discrepancy between this belief and their use of professional interpreters.