- Apr 2 WTAR (now WTKR) TV channel 3 in Norfolk, VA (CBS) begins broadcasting
- Apr 4 Dirk Stikker becomes chairman of OES
- Apr 5 Prague espionage trial against bishops & priests begins
Historic Event
Apr 6 John Foster Dulles becomes advisor to US Secretary of State Acheson
- Apr 8 "Miss Liberty" closes at Imperial Theater NYC after 308 performances
- Apr 9 14th US Masters Tournament, Augusta National GC: Jimmy Demaret becomes the first 3-time Masters champion by 2 strokes ahead of Australian Jim Ferrier
- Apr 9 4th Tony Awards: Cocktail Party & South Pacific win
Historic Event
Apr 11 Prince Rainier III becomes ruler of Monaco
- Apr 11 US B-29 bomber shot down over Latvia
- Apr 14 1st edition of British comic "Eagle"
- Apr 14 Doorne's Auto factory opens in Netherlands
- Apr 17 54th Boston Marathon won by Kee Yong Ham of South Korea in 2:32:39
- Apr 18 1st opening night-game, Cards beat Pirates, 4-2
- Apr 18 Polish Catholic church & government sign accord over relations
- Apr 18 Sam Jethroe is 1st African American to play for Boston Braves
- Apr 18 Yankees win 15-10 after trailing Red Sox 9-0 in 6th
- Apr 20 Balt's Memorial Stadium opens - Orioles of International League
- Apr 23 1st major league day game completed under lights (Phils 6, Braves 5)
- Apr 23 NBA Championship: Minneapolis Lakers beat Syracuse Nationals, 110-95 to take series, 4 games to 2
- Apr 23 Nationalist China evacuates Hainan Island
- Apr 23 Stanley Cup Final, Olympia Stadium, Detroit, MI: Pete Babando scores Cup-winning goal in double overtime of Game 7 as Detroit Red Wings beat NY Rangers, 4-3 for a 4-3 series win
Music Premiere
Apr 24 Leonard Bernstein's musical "Peter Pan", starring Jean Arthur and Boris Karloff, opens at Imperial Theater, NYC; runs for 320 performances
- Apr 24 Independent republic of South Molukkas declared
- Apr 24 US President Harry Truman denies there are communists in the US government
- Apr 24 Jordan formally annexes the West Bank
- Apr 25 Republik Maluku Selatan (also known as the Republic of the South Moluccas) declared on Ambon
- Apr 25 Chuck Cooper becomes the 1st African American to be drafted into the NBA (for Boston Celtics)
- Apr 26 Last horse race at Havre de Grace Track in Md, is run
- Apr 26 U of Miami ends William & Mary straight tennis match victories at 82
- Apr 27 "Tickets, Please" opens at Coronet Theater NYC for 245 performances
- Apr 27 South Africa passes Group Areas Act segregating races