YH-19 - Five early production S-55s for evaluation.

H-19A - USAF version of the YH-19 powered by a 600hp R-1340-57 engine, redeisgnated UH-19A in 1962, 50 built.

SH-19A - H-19As modified for Air-Sea Rescue, redesignated HH-19A in 1962.

H-19B - H-19A with a more powerful 700hp R-1300-3 engine, redesignated UH-19B in 1962, 264 built.

SH-19B - H-19Bs modified for Air-Sea Rescue, redesignated HH-19B in 1962.

H-19C - US Army version of the H-19A, redesignated UH-19C in 1962, 72 built.

H-19D - US Army version of the H-19B, redesignated UH-19D in 1962, 301 built.

HO4S-1 - US Navy version of the H-19A, 10 built.

H04S-2 - Project for rescue version for the United States Coast Guard, not built.

H04S-3 - Re-engined US Navy & Canadian version with 700hp R-1300-3 engine, redesignated UH-19F (American variant) H04S-3 (Canadian variant) in 1962, 79 built.

HO4S-3G - United States Coast Guard version of the HO4S-3, redesignated HH-19G in 1962, 30 built.

HRS-1 - United States Marine Corps version of the HO4S for eight troops, 60 built.

HRS-2 - HRS-1 with equipment changes, 101 built.

HRS-3 - HRS-2 with a 700hp R-1300-3 engine, became CH-19E in 1962, 105 built and conversions from HRS-2.

HRS-4 - Project for HRS-3 with a 1025hp R-1820 radial engine, not built.

UH-19A - H-19A redesignated in 1962.

HH-19A - SH-19A redesignated in 1962.

UH-19B - H-19B redesignated in 1962.

HH-19B - SH-19B redesignated in 1962.

CH-19E - HRS-3 redesignated in 1962.

UH-19F - HO4S-3 redesignated in 1962.

HH-19G - HO4S-3G redesignated in 1962

S-55 - Commercial version with 600hp R-1340 engine.

S-55A - Commercial version with 800hp R-1300-3 engine.

S-55C - S-55A with a 600hp R-1340 engine.

S-55T - Modified aircraft with a 650shp Garrett-AIRResearch TSE331-3U-303 turboshaft and updated equipment.

S-55QT - Commercial conversion. Ultra-quiet helicopter for sight-seeing flights over the Grand Canyon.

OHA-S-55 Heli-Camper - Commercial conversions carried out by Orlando Helicopters.

OHA-S-55 Nite-Writer - Commercial conversion. Aerial advertising helicopter, fitted with a 12.2-m x (40-ft x 8-ft) array of computer-controlled lights.

OHA-S-55 Bearcat - Commercial conversion. Agricultural helicopter.

OHA-S-55 Heavy Lift - Commercial conversion. Flying crane helicopter.

QS-55 Aggressors - Commercial conversion. S-55 helicopters converted into flying targets.

OHA-AT-55 Defender - Commercial conversion. Armed military helicopter.

Whirlwind HAR21 - HRS-2 for Royal Navy, ten delivered.

Whirlwind HAS22 - H04S-3 for Royal Navy, 15 delivered.