Summary: The isotopic ages of three biotites from the Kondapalli area, Andhra Pradesh, India, have been determined by the ⁴⁰Ar/⁴⁰K method. The results (440–524 Myr) indicate that the basic charnockite and khondalite of pre-Cambrian age have been subjected to at least one subsequent metamorphism the age of which must be 440 Myr or younger. The significance of the results is discussed in the light of the available geochronological evidence from Peninsular India.