# 1970 US Open – Mixed doubles

Marty Riessen and Margaret Court were the defending champions and successfully defended their title, defeating Frew McMillan and Judy Dalton 6–4, 6–4 in the final.
This was the first edition to feature a tie-break. It was used a sudden-death tie-break in all sets, winning the first to reach 5 points.

## Seeds

* Marty Riessen / Margaret Court (champions)
* Alex Metreveli / Olga Morozova (second round)
* Frew McMillan / Judy Dalton (final)
* Dennis Ralston / Françoise Dürr (semifinals)

## Draw
### Key

* Q = Qualifier
* WC = Wild card
* LL = Lucky loser
* Alt = Alternate
* SE = Special exempt
* PR = Protected ranking
* ITF = ITF entry
* JE = Junior exempt
* w/o = Walkover
* r = Retired
* d = Defaulted
* SR = Special ranking

### Finals

| Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
| 1 | Marty Riessen Margaret Court | 7 | 3 | 6 | | | | | | | | | |
| | Tom Gorman Denise Carter | 5 | 6 | 2 | | | | | | | | | |
| | Tom Gorman Denise Carter | 5 | 6 | 2 | 1 | Marty Riessen Margaret Court | 6 | 6 | 6 | | | | |
| | | | | | 4 | Dennis Ralston Françoise Dürr | 3 | 7 | 3 | | | | |
| 4 | Dennis Ralston Françoise Dürr | 6 | 6 | | 4 | Dennis Ralston Françoise Dürr | 3 | 7 | 3 | | | | |
| | Bob Carmichael Gail Chanfreau | 3 | 1 | | | | | | | | | | |
| | Bob Carmichael Gail Chanfreau | 3 | 1 | | | | | | | 1 | Marty Riessen Margaret Court | 6 | 6 |
| | | | | | | | | | | 3 | Frew McMillan Judy Dalton | 4 | 4 |
| | Cliff Richey Nancy Richey | 1 | 3 | | | | | | | | | | | 3 | Frew McMillan Judy Dalton | 4 | 4 |
| 3 | Frew McMillan Judy Dalton | 6 | 6 | | | | | | | | | | |
| 3 | Frew McMillan Judy Dalton | 6 | 6 | | 3 | Frew McMillan Judy Dalton | 7 | 6 | | | | | |
| | | | | | | Roger Taylor Nell Truman | 5 | 3 | | | | | |
| | Owen Davidson Rosie Casals | 6 | 6 | | | Roger Taylor Nell Truman | 5 | 3 | | | | | |
| | Roger Taylor Nell Truman | 7 | 7 | | | | | | | | | | |

### Top half
#### Section 1

| Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| 1 | M Riessen M Court | 7 | 6 | | | | | | | | | | |
| | B Howe D Hard | 6 | 0 | | | | | | | | | | |
| | | | | | 1 | M Riessen M Court | 6 | 6 | | | | | |
| | | | | | | L Miller M-A Curtis | 2 | 2 | | | | | |
| | L Miller M-A Curtis | 6 | 6 | | | | | | | | | | |
| | G Taylor B-A Hansen | 3 | 4 | | | | | | | | | | |
| | | | | | | | | | 1 | M Riessen M Court | 7 | 3 | 6 |
| | | | | | | | | | | T Gorman D Carter | 5 | 6 | 2 |
| | P Guzmán E Emmanuel | 5 | 6 | 6 | | | | | | | | | |
| | O Bengtson C Sandberg | 7 | 3 | 4 | | | | | | | | | |
| | | | | | | P Guzmán E Emmanuel | 4 | 1 | | | | | |
| | | | | | | T Gorman D Carter | 6 | 6 | | | | | |
| | D Dell I Bentzer | 2 | 5 | | | | | | | | | | |
| | T Gorman D Carter | 6 | 7 | | | | | | | | | | |

#### Section 2

| First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| | | | 4 | D Ralston F Dürr | 6 | 3 | 7 | | | | | | | | |
| | | | | P Cornejo P Teeguarden | 3 | 6 | 5 | | | | | | | | |
| | | | | | | | | 4 | D Ralston F Dürr | 6 | 7 | | | | |
| | | | | | | | | | E Scott C Martinez | 2 | 6 | | | | |
| | | | | S Ross P Bartkowicz | 4 | 4 | | | | | | | | | |
| | | | | E Scott C Martinez | 6 | 6 | | | | | | | | | |
| | | | | | | | | | | | | 4 | D Ralston F Dürr | 6 | 6 |
| | | | | | | | | | | | | | B Carmichael G Chanfreau | 3 | 1 |
| | | | | B Carmichael G Chanfreau | 6 | 6 | | | | | | | | | |
| | | | | B Salembier P Hogan | 3 | 0 | | | | | | | | | |
| | | | | | | | | | B Carmichael G Chanfreau | w/o | | | | | |
| | | | | | | | | | D Crealy K Melville | | | | | | |
| | | | | R Ruffels V Wade | 3 | 7 | 6 | | | | | | | | |
| K Stuart K Harris | 2 | 3 | | D Crealy K Melville | 6 | 6 | 7 | | | | | | | | |
| D Crealy K Melville | 6 | 6 | | | | | | | | | | | | | |

### Bottom half
#### Section 3

| First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| J-B Chanfreau L Hunt | 6 | 6 | | | | | | | | | | | | | |
| V Korotkov M Kroschina | 2 | 3 | | J-B Chanfreau L Hunt | 4 | 6 | 5 | | | | | | | | |
| | | | | R Russell S Holdsworth | 6 | 3 | 7 | | | | | | | | |
| | | | | | | | | | R Russell S Holdsworth | | | | | | |
| | | | | | | | | | C Richey N Richey | w/o | | | | | |
| | | | | C Richey N Richey | 6 | 6 | | | | | | | | | |
| | | | | P Fishbach M Aschner | 2 | 4 | | | | | | | | | |
| | | | | | | | | | | | | | C Richey N Richey | 1 | 3 |
| | | | | | | | | | | | | 3 | F McMillan J Dalton | 6 | 6 |
| | | | | A Stone P Walkden | 6 | 7 | | | | | | | | | |
| | | | | A Olmedo K Kemmer | 2 | 6 | | | | | | | | | |
| | | | | | | | | | A Stone P Walkden | 3 | 5 | | | | |
| | | | | | | | | 3 | F McMillan J Dalton | 6 | 7 | | | | |
| | | | | M Machette S Walsh | 6 | 1 | 1 | | | | | | | | |
| | | | 3 | F McMillan J Dalton | 4 | 6 | 6 | | | | | | | | |

#### Section 4

| Second round | Second round | Second round | Second round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals |
| | F Stolle H Gourlay | 4 | 1 | | | | | | |
| | B Fairlie K Pigeon | 6 | 6 | | | | | | |
| | | | | B Fairlie K Pigeon | 2 | 6 | | | |
| | | | | O Davidson R Casals | 6 | 7 | | | |
| | O Davidson R Casals | 6 | 6 | | | | | | |
| | MA Ilahi P Stewart | 0 | 1 | | | | | | |
| | | | | | | | O Davidson R Casals | 6 | 6 |
| | | | | | | | R Taylor N Truman | 7 | 7 |
| | J Fillol K Harter | 7 | 6 | | | | | | |
| | P Curtis S Johnson | 6 | 4 | | | | | | |
| | | | | J Fillol K Harter | 5 | 4 | | | |
| | | | | R Taylor N Truman | 7 | 6 | | | |
| | R Taylor N Truman | 7 | 6 | | | | | | |
| 2 | A Metreveli O Morozova | 5 | 2 | | | | | | |