INTRODUCTION: A large body of evidence suggests a connection between maternal infection during pregnancy and increased risk of developing autism spectrum disorder (ASD) in the child. One of the characteristic symptoms of ASD is deficits in communication. Rodent models of ASD include the administration of a synthetic double-stranded RNA, the polyinosinic-polycytidylic acid (poly(I:C)) to the pregnant dam, that evokes an antiviral‑like immune reaction. Rat pups isolated from their mother emit calls within ultrasonic spectrum of ~40 kHz. AIM(S): In this study, we examined whether poly I:C pups presented an altered pattern of ultrasonic vocalization (USV) during the mother isolation test. METHOD(S): Pregnant Sprague-Dawley dams received an intraperitoneal injection of poly I:C (5 mg/kg) or vehicle on GD 15. The isolation of male and female offspring was performed on PND 6. RESULTS: We observed changes in the number of vocalisations and an altered structure of emitted calls. Poly I:C males emitted less calls than control animals. A similar change in females was not observed. Both male and female poly I:C pups emitted calls of lower call bandwidth and peak frequency. CONCLUSIONS: Such changes of the structure of emitted calls suggest an impairment of vocal communication in the poly I:C animals. A decrease in the number of emitted calls in poly I:C males may reflect the fact that the prevalence and severity of symptoms of ASD is higher in boys and it appears that this higher susceptibility of males is present also in the poly I:C model. FINANCIAL SUPPORT: This study was supported by the Polish National Science Centre grant NCN 2016/23/B/NZ7/01131.