Simultaneous communication combines spoken English with manual representations of English words by signs and fingerspelling. The purpose of this investigation was to study the effect of sign complexity on temporal features of speech during simultaneous communication (SC). The effects of three independent variables: (a) mode (speech only versus SC); (b) sign complexity (base versus elaborated signs); and (c) type of sign movement (kinetic versus morphokinetic) were studied on five dependent variables: (a) word duration, (b) sentence duration, (c) diphthong duration, (d) interword-interval before signed experimental word (IWIB), and (e) interword-interval after signed experimental word (IWIA). Audio recordings were made of 12 normal-hearing, experienced sign language users speaking experimental words that varied in sign complexity and movement under SC and speech only (SO) conditions. Results indicated longer sentence durations for SC than SO and longer anticipatory durations of IWIB and diphthong before signed words, especially those using more complex signs. IWIA only lengthened for SC vs SO with no further effect of sign complexity. These results indicate a finite effect of sign complexity on pause and segment durations before the sign but not as strong an effect as has been reported for increased fingerspelling complexity.