The Asian monsoon exhibits significant variability on many timescales. On the interannual timescale, one of the most significant observations is the inverse relationship between monsoon strength and El Nino Southern Oscillation (ENSO). Typically, a warm ENSO event corresponds to weak seasonal monsoon precipitation while a cold ENSO event corresponds to strong strong seasonal precipitation (Webster and Yang 1992). However, not all deficient monsoon rainfall seasons occur during warm ENSO events. On the intraseasonal timescale, precipitation is characterized by distinct active and break periods of rainfall that are associated with the northward propagating arm of the tropical 30-60 day oscillation. Recent modeling studies indicate that ENSO may modulate these low frequency intraseasonal oscillations (Krishnan and Kasture 1996). In the model, during a warm ENSO episode, the 30-60 day oscillation is amplified relative to normal and oscillates at a lower frequency. Preliminary investigations using the 40 year record of the National Center for Environmental Prediction (NCEP) reanalyses support these model results. A strong correlation is found between the seasonal monsoon performance and the intraseasonal oscillation amplitude and period regardless of the ENSO phase. The reduction in seasonal precipitation during seasons of robust intraseasonal oscillation activity appears to be attributable to more thorough and extended break periods that disrupt the relatively steady rainfall typical of the monsoon season. Conversely, during seasons of reduced or neglible intraseasonal oscillation activity, the seasonal precipitation is, by and large, above normal due to the absence of significant break episodes.