The performance of the rodenticide 5-p-chlorophenyl silatrane at 0.5% in a wholemeal flour/pinhead oatmeal/corn oil bait was compared with that of zinc phosphide at 3% in the same base in poison treatments carried out against urban infestations of the house mouse (Mus musculus L.). Each poison treatment was conducted for 1 day and after 3 days' pre-baiting. The success of the treatments was assessed from census baitings conducted before and after treatment. Treatment success varied considerably with both poisons used but in general 5-p-chlorophenyl silatrane proved to be at least as effective as zinc phosphide, a commonly used acute rodenticide for the control of mice.