To examine the neural correlates of spoken idiom comprehension, we conducted an event-related functional MRI study with a 'rapid sentence decision' task. The spoken sentences were equally familiar but varied in degrees of 'idiom figurativeness'. Our results show that 'figurativeness' co-varied with neural activity in the left ventral dorsolateral prefrontal cortex, which involved two different clusters: one cluster engaged Broca's area (Brodmann area, BA: 44 & 45) and adjacent regions (BA 11 & 47); the other cluster involved the superior and medial frontal gryrus (BA 8 & 9). Moreover, the comparison between unambiguous, explicit idiomatic and literal sentences revealed left-sided cluster activity in Broca's area and BA 46 & 47. The contrast between ambiguous idiomatic and literal sentences engaged the superior and medial of the frontal midline (BA 9 & 10), but with left-sided prevalence. Finally, we report a very consistent deactivation in the superior parietal cortex by explicit idiomatic sentences as compared to literal sentences. Our findings are discussed in context of a neurological model of spoken language processing.