Porcine reproductive and respiratory syndrome virus (PRRSV) infection is the leading cause of economic casualty in swine industry worldwide1,2. The virus can cause reproductive failure, respiratory disease, and growth retardation in pigs. Vaccination with modified live vaccines (MLV) is still the principal means used to control PRRSV infection. This report presents observations made with a new genotype 1 based MLV against PRRS (UNISTRAIN®) in Germany. The main aim was the evaluation of reproductive parameters after a change in the vaccine.