The 1998 blockbuster Kuch Kuch Hota Hai marked the directorial debut of Karan Johar
Shah Rukh Khan and Kajol had already promised Karan that they would star in his first film when he was assisting Aditya Chopra while filming DDLJ
But several actors rejected him for the supporting roles, which were eventually played by Rani Mukerji and Salman Khan
Karan had written the second female lead role keeping Twinkle Khanna in mind because he even named the character Tina. But Twinkle refused to do the film.
Chandrachur Singh was already shooting for four films and hence, couldn't do Kuch Kuch Hota Hai
Raveena Tandon was restarting her career after a sabbatical and hence, didn't want to play a second lead
Karan has confirmed that Saif Ali Khan had also refused the film
Aishwarya Rai Bachchan found the role similar to what she had done previously and thus, refused Karan Johar
Karisma Kapoor had already played the second lead in Dil To Pagal Hai so she refused to work in Kuch Kuch Hota Hai