This study investigates how the El Ni?o-South Oscillation (ENSO) modulates the intraseasonal variability (ISV) of Pacific-Japan (PJ) teleconnection patt. The PJ index during boreal summer is constructed from the em-pirical orthogonal function (EOF) of the 850-hPa zonal wind (U850) anomalies. Distinct periods of the PJ index are found during El Ni?o and La Ni?a summers. Although ISV of the PJ patt is significant during 10-25 days for both types of summers, it peaks on Days 30 and 60 in El Ni?o and La Ni?a summers respectively. During El Ni?o sum-mers, the 30-day ISV of PJ patt is related to the northwestward propagating intraseasonal oscillation (ISO) over the west North Pacific (WNP), which is originated from the tropical Indian Ocean (IO). During La Ni?a summers, the 60-day ISV of PJ patt is related to the northeastward propagating ISO from the tropical IO. The low-fre-quency ISV modes in both El Ni?o and La Ni?a summers are closely related to the boreal summer ISO (BSISO), and the high-frequency ISV modes over WNP are related to the quasi-biweekly oscillation. The underlying mechanisms for these different evolutions are also discussed.