Brassica species may provide attractive alternatives to rye as winter cover crops for reducing N leaching from cropland in the Mid-Atlantic Region. The N capture potential was studied, including plant biomass N, soil profile (upper 120 to 180 cm) mineral N (NH4+NO3), and soil porewater NO3-N and total nitrogen (TN) (at 90 or 120 cm), of forage radish (Raphanus sativus cv. Dichon), oilseed radish (Raphanus sativus cv. Adagio), rapeseed (Brassica napus cv. Dwarf Essex), rye (Secale cereale) and winter weeds (control) at three Maryland Atlantic coastal plain locations from August 2003-May 2005. At Bowie, (Galestown-Evesboro loamy sand), total N uptake by late fall 2003 averaged 126-142 kg N/ha in the radishes, and total NO3-N in the upper 180 cm of soil (kg N /ha) averaged 154 under control and 56-60 under the Brassicas with significant mineral N reductions occurring as deep as 165 to 180 cm. At Beltsville (Elkton silt loam), plant N uptake by late fall 2003 ranged from 97-112 kg/ha for forage radish and rape. Nitrate-N (kg/ha) in the soil profile (0-120 cm) was 68 under control, 26 and 31 under forage radish and rapeseed respectively. At Wye (Matapeake silt loam), nitrate-N (0-120 cm) was 49 kg N/ha under control, 27 under rye, and 17-26 under Brassicas. If established by early September, Brassicas were at least as effective as rye in capturing excess soil N. No differences in NO3-N due to treatment were observed at any site in spring 2004. Soil porewater NO3-N and TN concentrations under cover crops did not differ from the controls. Concentrations of both NO3-N and TN in porewater varied with time as a function of decomposition and precipitation, with maximum concentrations between mid-March and mid-April 2004.