Whole rock chemical analysis was carried out for sillimanite-cordierite-biotite-garnet (Sil-Crd-Bt-Grt) gneisses at Ktiš in the Lhenice shear zone of the southern Bohemian Massif, Czech Republic, in order to consider the origin of this rock. The Sil-Crd-Bt-Grt gneiss shows a variety of lithotype mainly controlled by modal amount and grain size of main constituent minerals, resulting in the wide chemical variation of SiO2 content even in one outcrop from mafic composition (48.5 wt％) of a melanocratic layer with coarse-grained Grt to felsic composition (76.9 wt％) of a leucocratic vein. Petrology of the Sil-Crd-Bt-Grt gneiss and common occurrence of the leucosome in the outcrop suggest that the study rock suffered the partial melting during the exhumation stage. Available geochemical data suggest that leucocratic lithotypes with SiO2 contents from 70.3 to 76.9 wt％ were formed by the partial melting of the protolith and melanocratic types with SiO2 contents from 48.5 to 60.6 wt％, which include the main lithotype, were the residue. Therefore, leucocratic/melanocratic layer intercalations with SiO2 contents from 57.0 to 65.0 wt％ would most likely represent the chemical composition of the protolith of Ktiš gneiss. Several lines of chemical features of the leucocratic/melanocratic layer intercalation suggest that the protolith would be a mixture of greywacke and pelite with moderate aluminum saturation index (ASI) value and is characterized by extreme high Fe2O3 compared with continental and trench fill sediments.