Persian carpets have entailed assorted designs, patterns and ornaments of which this paper focused on calligraphy. The use of calligraphy in carpets along with other elements entails some themes and concepts. These themes include some ayahs, hadiths, and poems as well as the weaver or the designer's signature. This study answered the question that what concepts and themes have been used in the carpet epigraphs preserved in the Victoria and Albert Museum (London) and the Metropolitan Museum of Art (New York). The aim of this study was the historical, literary and religious investigation and analysis the epigraphs on carpets kept at the mentioned museums. This qualitative study was conducted using a descriptive-analytic design. Data were collected using librarian method and collecting pictures from two Museums of Art websites. Results suggested that in the carpets investigated in this study, three themes, namely historical (name of the weaver or order submitter), literary (in the form of sonnets, odes or quatrains) and religious (ayahs from the Quran or the Bible) were found in the epigraphs in Thuluth, Naskh, Nastaliq, Towqi and Hebrew calligraphies. While the historical epigraphs indicate the date of weaving, the weaver and his/her performance in a sentence, religious epigraphs describe the creator and the literary epigraphs describe the springtime, the lover, and seizing the opportunity of a lifetime. These epigraphs were designed in the form of rectangle, Bazoobandi and Ghalamdani which are mainly found on the main border, the field, the guard border, and the medallion or a combination of them respectively.