Israeli carp (Cyprinus carpio) eggs were cold-shocked after fertilization at various temperature regimes and durations. Nine months later their hlood was sampled for analysis. Stained erythrocyte nuclei were measured with an ocular micrometer to calculate mean relative areas. Polyploidy appeared to have heen induced in each coldshock group, hut no group appeared to consist entirely of polyploids. Gonadal examination showed no apparent differences hetween the control group and the cold-shocked groups.