Objective of this study was to assess the tissue compatibility of a vaccination, combining vaccines against Haemophilus parasuis and Porcine Reproductive and Respiratory Syndrome Virus (PRRSV). Clinical examinations were done with special respect to local tissue reactions after injection of 2 ml each of either Porcilis Glasser, or Porcilis PRRS (both Intervet, Unterschleissheim, Germany), or a mixture of the two vaccines. Animals were euthanized on day six post vaccination. Clinical as well as gross pathological or histological alterations at the injection sites were similar in all groups and were predominantly low grade. Clinical investigation of the injection sites revealed a mild increase in tissue consistency as well as mild swelling and reddening after the application of Porcilis PRRS and the mixture of the two vaccines. In the Porcilis Glässer group, few cases of moderately increased skin consistency and mild swelling were noted 4 hours post injection. Pathological examination showed mild haemorrhages and mild pallor of the tissue with a maximum linear width of 2 cm at the injection site in most animals. Histological examination predominantly revealed a mild lymphocytic reaction, which was generally restricted to the subdermal connective tissue. However, the study did not address the key outcome of combined vaccination, namely immunogenic power. Therefore, further immunological studies are warranted.