Birmingham - Lauren Winfield has scored her maiden half-century to lead England women to a nail-biting, eight-run victory over the Proteas at Edgbaston in Birmingham, England, on Sunday.
England's victory in this third and final Twenty20 (T20) match gives them a series whitewash over the visitors.
England posted 126/6 in their innings after being put in to bat by South Africa.
Winfield scored 74 runs off 60 balls, including nine fours and the first six of the series, to put her side in a strong position before she departed in the 17th over.
The visitors produced their strongest bowling performance in the series, taking six wickets thanks to Chloe Tryon (2/18), Dan van Niekerk (1/16) and Matshipi Letsoalo (1/18).
Marizanne Kapp (1/24) was the first bowler to strike, removing England skipper Charlotte Edwards for four in the third over. Sarah Taylor followed for nine at the hands of Letsoalo.
South Africa's fielding improved with each match. Sun Luus took a brilliant catch to get rid of Winfield, while wicketkeeper Trisha Chetty was brilliant behind the stumps, removing Natalie Sciver for four and taking an impressive catch to get rid of Heather Knight (8) off Tryon in the 19th over.
Shabnim Ismail (1/23) bowled Danielle Wyatt for a duck off the first delivery of the last over to restrict England to the modest total.
South Africa made a strong start with a solid 59-run opening stand between Van Niekerk and Chetty before the former was run out for a well-played 35 off 40 balls in the 11th over.
Lizelle Lee departed next, trapped lbw for nine by Jenny Gunn (2/18) at the end of the 14th over.
England's experience and ability to apply pressure won out in the end. Chetty (34) was run out by a direct hit by Lydia Greenway in the 16th over, then Proteas' captain Mignon du Preez was caught by Greenway in the deep off the next delivery for three.
Taylor pulled off an acrobatic run-out of Kapp (1) to leave South Africa on 89/5, needing 38 from 21 balls.
Tryon and Bernadine Bezuidenhout put on a promising partnership of 25 runs from 15 balls for the sixth wicket before newcomer Bezuidenhout was stumped for 12 at the end of the 19th over.
South Africa needed 13 from the last over, but good bowling by Katherine Brunt and tight fielding saw the visitors fall eight runs short of victory.
The Protea Queens, as they are known, will set their sights on Ireland in another three-match T20 series at the Moseley Cricket Club in Solihull, Birmingham, on September 9-10. They will play a double-header on Tuesday followed by the final on Wednesday before they return home.