Well, Kamal Haasan says he did 27 films with Sridevi but we only found these 21...
Oka Radha Idhdharu Krishnulu (1986) - Telugu
Aakhri Sangram (1984) - Hindi
Sadma (1983) - Hindi
Andhagaadu (1982) - Telugu
Moondram Pirai (1982) - Tamil
Vazhvey Maayam (1982) - Tamil
Aakali Rajyam (1981) - Telugu
Meendum Kokila (1981) - Tamil
Shankarlal (1981) - Tamil
Guru (1980) - Tamil
Guru (1980) - Telugu
Varumaiyin Niram Sivapu (1980) - Tamil
Kalyana Raman (1979) - Tamil
Neeka Malargal (1979) - Tamil
Sigapukal Mookuthi (1979) - Tamil
Thaillamal Nanillai (1979) - Tamil
Chakkaipodu Podu Raja (1978) - Tamil
Manitharil Ithanai Nirangala (1978) - Tamil
Sigapu Rojakkal (1978) - Tamil
16 Vayanthiniley (1977) - Tamil
Moonru Mudichu (1976) - Tamil
... anyone know what the other six are?