Of the eight changes, seven are in personnel, with one positional, to the side that beat The Pumas 29-17 in Resistancia last Saturday.
Rob Kearney comes in for Felix Jones at full back, while Fergus McFadden lines out in the centre at 13, with Darren Cave going to inside centre.
Jonathan Sexton will be partnered in the half-backs by Eoin Reddan at scrum-half.
David Kilcoyne will start in the front row with Rory Best and Mike Ross, while Devin Toner will be alongside captain Paul O'Connell in the second row.
Jamie Heaslip and Rhys Ruddock are brought into the back-row.
Meanwhile, three uncapped players will be on the bench; Ulster's Rob Herring, Munster's James Cronin and Leinster's Noel Reid.
Kick off in this evening's second Test in Tucuman is at 7:40pm Irish time.
Ireland XV to play Argentina: 15 Rob Kearney; 14 Andrew Trimble, 13 Fergus McFadden, 12 Darren Cave, 11 Simon Zebo; 10 Johnny Sexton, 9 Eoin Reddan; 1 Dave Kilcoyne, 2 Rory Best, 3 Mike Ross; 4 Devin Toner, 5 Paul O’Connell (captain); 6 Rhys Ruddock, 7 Chris Henry, 8 Jamie Heaslip.
Replacements: 16 Rob Herring, 17 James Cronin, 18 Jack McGrath, 19 Iain Henderson, 20 Jordi Murphy, 21 Conor Murray, 22 Ian Madigan, 23 Noel Reid.
