The invention comprises compounds of the formula: <;FORM:0790800/IV (b)/1>; wherein R and R1 are hydrocarbon, chlorine-substituted hydrocarbon, alkoxy, carbonyl, carbalkoxy-substituted hydrocarbon radicals or sulphur-containing heterocyclic radicals having between them 8 to 20 carbon atoms, X-is the anion of a therapeutically acceptable non-toxic acid and Z contains not more than 7 carbon atoms and is a carbalkoxy radical, carbamyl radical, N-dialkylcarbamyl radical, benzoyl radical, acetyl radical or hydrogen. Such compounds are obtained by quaternizing a compound of the general formula: <;FORM:0790800/IV (b)/2>; with a quaternizing agent of the general formula R1X where Z1 is a nitroso radical or an organic radical containing not more than seven carbon atoms and is a carbalkoxy, benzoyl, N-dialkylcarbamyl, carbamyl or acetyl radical, compounds wherein Z is hydrogen being prepared by the additional step of hydrolysing compounds wherein Z is a carbalkoxy radical or of hydrogenating compounds prepared from those wherein Z1 is a nitroso radical. In examples: (1) N-carbethoxy-N1-nonylpiperazine is reacted with methyl iodide to give N-carbethoxy - N1 - methyl - N1 - n - nonylpiperazinium iodide; (2) N - carbethoxy - N1 - methylpiperazine and n-dodecyl bromide are reacted to give N-carbethoxy-N1-methyl-N1-n-dodecylpiperazinium bromide; (3) N-nitroso-N1-benzylN1-methyl-piperazinium chloride is hydrogenated using a Raney nickel catalyst to give N-benzyl-N-methylpiperazinium chloride hydrochloride. In a generally similar manner to (1) there are prepared (4) N-carbethoxy-N1-allyl-N1(a - carbethoxyethyl) piperazinium bromide; (5) N - methyl - N - n - tridecylpiperazinium chloride hydrochloride; (6) N - benzoyl - N1-methyl - N1 - n - dodecylpiperazinium bromide; (7) N - dimethylcarbamyl - N1 - methyl - N1-benzylpiperazinium chloride; (8) N - carbethoxy - N1 - methyl - N1 - (2 - heptynyl) - piperazinium bromide. A list is given of similarly prepared compounds, the radicals in specific compounds being selected from (at Z) carbethoxy, carbomethoxy, benzoyl, acetyl, carbamyl, dimethylcarbamyl and hydrogen; (at R) methyl, ethyl, butyl, benzyl, phenethyl and allyl; and (at R1) heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, undecenyl, propynyl, heptynyl, benzyl, p-chlorobenzyl, 2,4-dichlorobenzyl, p-methoxybenzyl, o- and m-methylbenzyl, phenylallyl, benzoylmethyl, a - or b -thenyl, carbdodecyloxymethyl and a -carbethoxyethyl radicals. N - benzoyl - N1 - methylpiperazine and N - dimethyl - carbamyl - N1 - methylpiperazine are prepared by reaction of N-methylpiperazine with the appropriate acid chlorides.;FORM:0790800/IV>;FORM:0790800/IV>