A male patient suffering from ulcerative colitis, presented with primary infertility due to sulphasalazine therapy. Sulphasalazine was discontinued and the patient was treated with a 5-aminosalicylic acid preparation (Salofalk) in the form of an enema. After 3 months, the semen quality was dramatically improved and a successful pregnancy ensued. The sulphapyridine moiety of sulphasalazine seems to be responsible for male infertility and depressed semen quality. The metabolite 5-aminosalicylic acid is proposed as a suitable alternative to sulphasalazine in cases of male infertility.