A tertiary trisomic of the tomato, which originated as a spontaneous aberrant aneuploid in the progeny of triplo-5, was determined through pachytene analysis to involve the extra chromosome 5L·7S with breakpoints in either the centromere or proximal heterochromatin. The genes af and tf on 5S gave normal segregation with 2n+5L·7S while var on 7S gave trisomic segregation. Genetic confirmation for 5L was not obtained.