Oak woodlands and annual grasslands are a significant physiographic component in the foothill region of California and play a major role in the state's water supply system. In particular, there is concern of dissolved organic matter forming carcinogenic disinfection byproducts during drinking water chlorination and dissolved nitrogen contributing to downstream eutrophication. This study examined temporal changes in the quantity and quality of dissolved C and N in litter and duff leachates from blue oak, live oak, foothill pine and annual grass foliage over the course of the winter rainfall season. All leachates were analyzed for pH, electric conductivity (EC), suspended solid, total nitrogen (TN), total dissolved nitrogen (TDN), dissolved organic nitrogen (DON), ammonium (NH4), nitrate (NO3), total organic carbon (TOC) and dissolved organic carbon (DOC). EC value was highest in the annual grass duff treatment. While duff leachates often had high NH4 and NO3 concentrations, litter leachates had very low mineral nitrogen concentrations. Almost all of the mineral nitrogen in the duff leachates was NH4. TDN and DON were highest in the annual grass duff treatment. In contrast, more DOC was derived from litter than from duff and the highest DOC concentrations were found in blue oak litter leachate. DOC/DON ratios were relatively consistent over time in the duff treatments with values at 20 or below. In litter leachates, the DOC/DON gradually decreased over time, except for the annual grass treatment. This study indicates that relatively high concentrations of DOC, DON and mineral nitrogen can be transferred directly from litter and duff materials to streams by surface runoff and shallow subsurface lateral flow. It also may explain the high levels of dissolved carbon and nitrogen in stream waters during the earlier portion of the winter rainfall season.