Former North Harbour and Blues flanker Regan Tamihere and Hawkes Bay midfield back Sam Giddens have joined the union.
Tamihere played for Alhambra-Union on Saturday.
Otago coach Phil Mooney said both players would bring increased depth to the union's playing ranks.
Giddens had played 33 games for the Magpies before leaving to play overseas at the end of the 2009 representative season.
Formerly from Christchurch, Giddens was expected back in Dunedin later next month.
He debuted for Hawkes Bay in 2007, having played for Nelson Bays in 2005.
Giddens first left New Zealand to play for Bristol in England and after that club ran into financial difficulties and was relegated, he moved to Italy, to play for Lyons Piacenza last year.
Giddens (26) would add some strength to Otago's's playing roster in the midfield.
Midfield backs from last year Andrew Parata and Josh Tatupu have both left the union, although Ben Atiga has joined the province from Auckland, and Ben Smith can play in the midfield.
Tamihere (27) had played all 12 games for North Harbour in its 2006 Ranfurly Shield winning season but was then surprisingly dumped by new coach Wayne Pivac the next year.
He had played one game for the Blues, coming on as a substitute against the Waratahs in 2006.
Tamihere had not played much rugby in the past couple of years as he has concentrated on a career in the police force.
He had taken a leave of absence from the police to come south to play rugby and had the ability to play both sides of the scrum.
There is an opening at openside flanker with Otago, after incumbent and captain Alando Soakai said he was leaving to play in Japan at the end of the Highlanders season.
Mooney said the additions would create more competition among players, and that had to be a good thing.
Halfback Sean Romans had also signed for the union, and he and Johnny Legg would be the halfbacks in the Otago squad.
Mooney said the union was still looking for one or two players to complete the squad.
It had not yet been decided when players would be pulled out of club rugby but it was likely to be mid-June.
Otago's first game in the ITM Cup is on July 14, against North Harbour, at Carisbrook.
Otago signing Daniel Crichton's case was adjourned to April 29 in Dunedin District Court last Friday.
He was charged with assault, in a central city bar on April 3.
Otago Rugby Football Union general manager Richard Reid declined to comment on the incident as it was before the court.
