2005 Monte Carlo Masters

{{TennisEventInfo|2005|Monte Carlo Masters|

| date=11–17 April

| edition=99th

| category=ATP Masters Series

| prize_money=$2,220,000

| draw=64S / 24D

| surface=Clay / outdoor

| location=Roquebrune-Cap-Martin, France

| venue=Monte Carlo Country Club

| champs= {{flagicon|ESP}} Rafael Nadal{{cite web|title=2005 Monte Carlo – Singles draw|url=http://www.atptour.com/en/scores/archive/monte-carlo/410/2005/draws?matchType=singles|publisher=Association of Tennis Professionals (ATP)}}

| champd= {{flagicon|IND}} Leander Paes / {{flagicon|SCG}} Nenad Zimonjić{{cite web|title=2005 Monte Carlo – Doubles draw|url=http://www.atptour.com/en/scores/archive/monte-carlo/410/2005/draws?matchType=doubles|publisher=Association of Tennis Professionals (ATP)}}

}}

The 2005 Monte Carlo Masters was a men's tennis tournament played on outdoor clay courts. It was the 99th edition of the event and was part of the ATP Masters Series of the 2005 ATP Tour. It took place at the Monte Carlo Country Club in Roquebrune-Cap-Martin, France from 11 April through 17 April 2005. The men's singles was headlined by world No. 1 Roger Federer, Marat Safin and Tim Henman. Rafael Nadal won the singles title.