Heritability estimates and breeding value predictions of Dormer sires for litter size and lamb mortality were obtained using a threshold model. Heritability estimates on the underlying scale were 0.24 and 0.12 for litter size and mortality, respec¬tively. Breeding value predictions varied between 0.41σ2e and –0.43σ2e for litter size and 0.30σ22e and –0.14σ2e for lamb mortality. Probability distributions for progeny of sires across `fixed effects` were also calculated. It is concluded that a threshold model can effectively be applied for routine evaluation of Dormer sires for categorical traits.