We examine the evidence of an emerging yen block in North and Southeast Asia using up to 27 years of weekly data on 9 bilateral yen exchange rates. The exchange rate returns are modelled in response to variations in their US dollar, German mark, and UK pound effective counterparts using a general-to-specific dynamic estimation strategy. We also investigate the pattern of regional trade integration over time. The results suggest increasing intra-regional trade integration, particularly regarding Japanese trade integration with the region. They also indicate the decreasing influence of the US dollar in terms of magnitude, the German mark in terms of scope and the UK pound in terms of both magnitude and scope with respect to exchange rate determination in the region. These findings are consistent with an emerging yen influence although not a de facto yen block.