The present study confirms the findings of Zimmering and Bendbow [28], that there is preferential recovery of the shorter elements of asymmetric dyads following induced exchanges in irradiated T(2;-3)bwv4 males. Deletion studies giving rough estimates of contaminations of phenotypic crossovers by deletions (or point mutations) have now provided more accurate estimates of the degrees of non-randomness (c) in the regions studied. The significance of the V4 studies and their implications on the mechanisms of meiotic drive are discussed.