Antimycotically and antibacterially effective imidazole derivatives of the formula (1) ##STR1## in which R.sup.1, R.sup.2 and R.sup.3 are the same or different and are hydrogen and lower alkyl; R.sup.4 is hydrogen, lower alkyl or selected from unsubstituted or substituted cycloalkyl, benzyl and phenyl groups wherein the substituents are selected from halogen, lower alkyl, lower alkoxy, lower alkylthio, phenyl, cyano, nitro and amino, or wherein R.sup.4 is an unsubstituted or halosubstituted pyridyl, R.sup.5 is nitro or lower alkyl in any unsubstituted position of the imidazole ring, Ar is a phenyl group optionally substituted with at least one substituent which is halogen, lower alkyl, lower alkoxy or a C.sub.4 -C.sub.8 cycloalkyl, or wherein Ar is a benzyl group optionally substituted with a substituent of the type set forth for R.sup.4, X and Y are independently selected from oxygen (--O--) or sulfur (--S), n is an integer of from 1 to 5 inclusive and p is Zero or an integer of from 1 to 3 inclusive, and the addition salts of formula (1) compounds with pharmaceutically acceptable organic or inorganic acids; the formula (1) compounds and their addition salts as specified have a relatively low oral toxicity or/and an improved solubility and are suitable for use in human and veterinary medicine and for chemo-agricultural fungus control purposes. Suitable pharmaceutical compositions including the novel derivatives or/and their addition salts with acceptable acids as well as methods for producing such novel derivatives are disclosed.