The presence of zones of fracture concentration in unexposed rock may be partially assessed by measuring the concentrations of 4He and 222Rn in groundwater and soil gas. Helium 4 in groundwater and soil gas and 222Rn in groundwater were measured in the vicinity of two intersecting linements in Lehigh County, Pennsylvania. The limeaments are thought to mark deep fracture systems which provide conduits for the migration of 4He and 222Rn. High groundwater 4He concentrations revealed the presence of the two lineaments. Low groundwater 222Rn activities are found near the lineaments and qualitatively support a numerical model which relates low 222Rn activity to high fracture transmissivity. Radon 222 activity correlates most strongly with the presence of H2S in groundwater, implying that geochemical controls or groundwater circulation patterns strongly influence radon concentration. Soil gas concentrations of 4He barely exceeded background levels and did not reliably indicate the lineament zones. The data show that groundwater 4He concentrations may be used to identify fracture zones in unexposed bedrock. ¿ American Geophysical Union 1988