The invention relates to new pyrimidine compounds of formulawherein the variables have the meaning as indicated in the claims in free form and in salt form and optionally the enantiomers and geometrical isomers thereof. The compounds of formula (1) are useful in the control of parasites, in particular ectoparasites, in and on warm-blooded animals.本發明係關於具新穎具有下式之嘧啶化合物其中該等變數具有申請專利範圍中所指示之意義;呈游離形式及鹽形式;及其視情況之鏡像異構物及幾何異構物。該等式(1)化合物係有用於控制溫血動物中及其上之有害生物,特別是外寄生物。