Abstract: An electrical lead retainer (2) with compression seal (4) is provided for a terminal receptacle post (6) of an ignition coil tower for gasoline engines in corrosive environments, including the high tension lead in marine applications. An insulated electrical wire (16) is inserted into the post, and an annular grommet (20) around the wire is compressed against the post and against the wire to prevent moisture from creeping across the post opening and from creeping along the wire into the post opening. An end cap (22) has an aperture (28) through which the wire extends and has a pair of flexible outer locking tabs (24, 26) engaging the backside of a flange (14) on the post in snap-lock manner to hold the cap on the post and compress the grommet. The cap has an internal annular recess (34) forming a step shoulder (56) with the aperture (28) and compressing the grommet against an annular collar (10) on the post.