This paper describes the ultrastructure of ellipsosomes in the retinal cones of the Cyprinid Garra lamta. Ellipsosomes originate from ellipsoidal mitochondria by a process of hypertrophy, gradual disorganization of cristae and densification of matrix. A mature ellipsosome contains no cristae at all. The matrix is granular and highly electron-dense, more so than described earlier for any other teleosts. The individual cones bear 1-3 mature ellipsosomes in the scleral-end of ellipsoids. Some of their possible roles in vision are highlighted. © 1995 Oxford University Press.