The elimination into bovine milk of sulphonamides (sulphadimidine and sulphamethoxypyridazine) and dapsone following intramammary infusion was studied. Determination of sulphonamides and dapsone in milk was performed by a high performance liquid Chromatographic method with UV detection. The limit of quantification was 0.01μg/ml. Withdrawal times were established considering the maximum residue limits fixed by the European Community (100μg/kg for sulphonamides and 25μg/kg for dapsone). The diffusion of residues into milk from a quarter infused by the intramammary route to the untreated quarters was also studied.