The invention relates to novel liquid preparation comprising a substituted benzimidazol, preferably pimobendan as pharmaceutically active compound. In particular, the present invention relates to liquid preparation comprising an etherified cyclodextrin derivative, preferably in a concentration of about 20 to 70% (w/v) and said substituted benzimidazol, preferably in a concentration of about 0.005 to 0.15 % (w/w).