A connector port or "header" for an implantable medical device comprises a molded plastic connector module having a longitudinal bore formed therethrough and a plurality of slots formed inwardly of one side surface thereof and intersecting the longitudinal bore. The slots receive electrical contact members therein and individual seal members are inserted through the longitudinal bore between each of the contact members such that when the in-line terminal pin of a medical lead is inserted into the longitudinal bore, contacts on the lead terminal are aligned with and mate to the electrical contacts in the connector block. The seal members prevent body fluids from compromising the resulting electrical connection.