The author analyses the onomastic data of the ostraka from Chersonesus Taurica, which were for the most part published by Yu.G. Vinogradov and M.I. Zolotarev in the 1990s. He argues that there were no grounds for marking out Doric names as a specific group. One can only speak of the names written in the Doric dialect in Megaric or Eastern Ionic script. With the exception of Molpas, specifically Ionic names cannot be pointed out either. Identifying the ethnic structure of the earliest Chersonesian population, it is more advisable to consider not the names themselves, but the dialect and script of the ostraka: two of them were written in the Megaric alphabet, the rest in Eastern Ionic (Milesian). This fact proves Vinogradov's and Zolotarev's conclusion that migrants from Ionia and their descendants were among the original inhabitants of Chersonesus. One ostrakon (KPETINH[Z]) was obviously written by a Delian. The author lists other epigraphic evidence (4th-2nd century BC) in favour of the presence of Delian community in Chersonesus. In the first half of the 5th century BC Megaric, East Ionic, and probably Delian alphabets must have been used side by side in Chersonesus. A problem of greatest importance is that of the dates of the earliest ostraka. Vinogradov and Zolotarev believed that they dated from 500^80 BC. On the basis of only two characteristic letters (3-shaped sigma and crossed khi) they compared Megaric ostraka of Chersonesus with inscriptions from Megara of about 500^75 BC. However, Vinogradov and Zolotarev did not mention the epigram of Pollis from Megara (about 480^70 BC), which has a crossed khi, and a presumably Megaric inscription from Olympia (LSAG2. P. 442. A, about 475^50 BC), where letter shapes are completely identical to those of the Chersonesian ostraka (which is not the case with the parallels indicated by Vinogradov and Zolotarev). It is not improbable that those shapes continued to be used in the Megaric alphabet later, right up to the end of the 5th century BC, when the Ionic alphabet was adopted. Moreover, 3-shaped sigma was not originally Megaric and, most likely, reflects Attic influence. It cannot, therefore, be a reliable chronological indicator in an inscription of the 5th century BC. The author finds no grounds to believe that any of the Chersonesian ostraka written in the Ionic alphabet dates from 500-480 BC. The earliest ostraka must not be older than 480-450 BC.