AbstractThe chemical composition of 12 commercial mineral supplements specially designed for sheep by 10 manufacturers are detailed together with the amounts of each element provided by a daily consumption of 15 g. All the supplements would provide at least 50% of the calcium requirement of a pregnant or lactating ewe. Similarly, most of the mixtures would supply 15–35% of the total desirable phosphorus intake but one provided only 6% and two would give about 45% of the daily requirement. None of the supplements generally manufactured for sheep contain adequate prophylactic amounts of magnesium for prevention of hypomagnesaemia, but the cattle supplements which are normally recommended by the respective firms would do so if used at the correct rates. All the supplements provided fully adequate amounts of cobalt, but three of the materials would have insufficient copper to prevent swayback. It is considered that there is an adequate safety margin against copper poisoning for all the supplements if fed in controlled amounts for restricted periods.