Erroneous stress placement (ESP) in the target language is one of the salient suprasegmental features of simultaneously interpreted texts. This paper investigates the phenomenon in simultaneous interpretation from English, a free stress language, into Hungarian, a fixed stress language, the aim being to ascertain whether ESPs are related to source language features. Analysis of an experimental corpus collected for an earlier study (Bóna & Bakti 2009) made it possible to identify 122 ESPs, divided into two categories: (a) related to source language features; (b) others. These categories were further divided into several subcategories. Thus, (a) included ESPs related to: (i) source language stress, with semantic correspondence between the source language and target language units concerned; (ii) source language stress, but with no semantic correspondence between the target language unit and the prosodically similar source language unit identified in relatively close proximity to it. For (b), the subcategories distinguished between ESPs related to: (iii) the phonetic target language context; (iv) translation problems; (v) individual speech characteristics. Our results provide support for the view that metrical planning and segmental planning are separate processes. Thus, successful inhibition of source language interference on the segmental level during simultaneous interpreting is not necessarily associated with suppression of suprasegmental level source language interference.