A collision with a U.S. destroyer escort off the north coast of Panama while submerged caused major damage to the periscope shears and radar, requiring a return to Portsmouth just at the time that Germany surrendered.

After repairs and Air/Sea Rescue modifications, Medregal departed New London, Connecticut, on 16 June, and steamed to participate in final operations in the Pacific against the Japanese.

The surrender of Japan halted her long Pacific voyage and she returned to the Canal Zone, thence to Key West, Florida, for operations with Submarine Squadron 4.

From late 1945 to mid-1957 Medregal operated out of Key West, training Reserves, supporting activities of the Fleet Sonar School, and taking part in antisubmarine warfare exercises.

Her cruises sent her along the east coast from Florida to Virginia, into the Gulf of Mexico and the Caribbean Sea, and to operating areas in the western Atlantic.

In May 1962, Medregal and USS Carbonero, SS-337 participated in Operation Dominic I, Shot Frigate Bird near Christmas Island (now Kiribati).

After reaching Yokosuka on 15 July, she joined Seventh Fleet aircraft carriers and destroyers for ASW operations in the western Pacific, and readiness and alert maneuvers with ships of the Republic of China Navy (based in Taiwan).

In January 1967, Medregal returned to her home port in Hawaii where she resumed her type training and squadron exercises with SubRon 1.

Stops included Hawaii, Guam, Viet Nam(twice), Subic Bay/Manila (Philippines), Chinhae (South Korea), Yokosuka/Kobe (Japan), Kaohsiung (Taiwan) and Hong Kong.