We examined involvement mucus in liquid-based cytology (LBC) technology such as TACAS. All 2970 samples for gynecological mass screening from May 2009 to March 2010 were prepared by using TACAS and/or SurePath. We compared 869 cases using TACAS with 2101 cases using SurePath. The rate of inadequate cases and uneven dispersion specimen using TACAS were much worse than those using SurePath, although there were no significant differences in Papanicolaou staining properties. It is considered to be dependant on mucus-rich materials, so mucus in specimen preparation with LBC technology such as TACAS or ThinPrep requires careful attention.