P. Vasu on the success of his Kannada film Apthamitra (2004) and was impressed with the film's screenplay. Vasu then requested to remake the film in Tamil with Rajinikanth, who in turn, called Ramkumar Ganesan and asked him to produce it under Ramkumar's banner, Sivaji Productions. Ramkumar telephoned Vasu, who was offering worship in a temple in Guruvayur at that time, informing him of Rajinikanth's wish to do Apthamitra in Tamil under his direction. Vasu reworked the script he wrote for Apthamitra to suit Rajinikanth's style of acting. The film dealt mainly with the concept of dissociative identity disorder, commonly known as "multiple personality disorder" (MPD) or "split personality disorder". Another film titled Anniyan (2005), which was released two months after Chandramukhi, was also based on the same disorder. Thota Tharani was the film's art director, and also designed the costumes. Regarding the designing of the Vettaiyapuram palace, he watched both Apthamitra and its source Malayalam film Manichitrathazhu (1993) to get the basic idea of the film's plot. Vasu wanted Tharani to make the sets more colourful and grand and did not want the realistic look of the original film. Tharani designed Chandramukhi's room and placed a corridor in it, which was quite different from the original and its Kannada remake. The corridor resembled those commonly seen in palaces in Kerala. Sidney Sladen did additional costume designing in the film. Casting Rajinikanth played the roles of Dr. Saravanan and King Vettaiyan. He sported a wig for his role. Both Rajinikanth and P. Vasu discussed every scene featuring the former and added necessary inputs before they were shot. Rajinikanth appears in the beginning of the film unlike Manichitrathazhu, where the same character, played by Mohanlal, appears in the middle of the film. Rajinikanth requested Vasu to change the dancer's name from Nagavalli, which was the name of the danseuse in Apthamithra, to Chandramukhi since the latter sounded more royal. While Vishnuvardhan uttered "Haula Haula" in the original, Rajinikanth used "Lakka Lakka", which was based on the mannerisms of a villain in a Marathi play Rajinikanth watched in his childhood days. Ramkumar's brother Prabhu played Senthilnathan, a civil engineer and owner of Ganesh Constructions. Prabhu co-produced the film with Ramkumar. For the roles of Ganga and Chandramukhi, Soundarya was initially selected to reprise her role from Apthamithra, but her death led the director to choose Simran and he shaped the character to