The aim of the present exploratory correlational study was to test whether a relationship exists between working memory capacity (WMC) and simultaneous interpreting (SI) performance measures in a sample of professional interpreters. Twenty-eight professional interpreters, aged 25-55, were tested on WMC tasks (letter span, Corsi task, complex span) and on several measures of SI (lexical, semantic and syntactic processing, temporal delay, vocabulary richness and dealing with speed). Additionally, general cognitive ability, age and interpreting experience were considered.