Abstract. Delforge, P. - Contribution to the knowledge of the Orchids of the island of Ikaria (East Aegean islands, Greece). After a presentation of the geology, the geomorphology, the climate, the vegetation, and the human impact over the landscape of the island of Ikaria, a review of the past and present studies and research about its orchids is presented. It appears that 26 orchids species were known for Ikaria before 2008 (Table 1). Research on Ikaria in March 2008 has revealed 19 orchid species for the island, bringing their number up to 31 (Table 1). First mentions are made for Ophrys basilissa, O. cinereophila, O. sitiaca s. str., O. pelinaea, and O. parosica var. parosica. Among the 31 species known at the present for the island, 10 are represented by few individuals (Herorchis picta var. caucasica, Himantoglossum comperianum, H. robertianum, Ophrys basilissa, O. phryganae, O. sitiaca s. str., Orchis anthropophora, O. italica, O. quadripunctata, and Paludorchis laxiflora) among which 4, not seen in 2008, are probably sporadic or extinct (Himantoglossum comperianum, Orchis italica, O. quadripunctata, and Paludorchis laxiflora). After carefull examination of “critical” plants as well as photographs, published or not, it appears that numerous old or recent mentions of orchids, made for Ikaria, are questionable or erroneous. All the mentions of O. spruneri, O. ferrum-equinum, O. fuciflora, O. holoserica, O. oestrifera, O. [oestrifera subsp.] bremifera, and O. scolopax concern O. icariensis, a very varied species, probably hybridogenous; mentions of O. fusca, O. leucadica and late-flowering O. sitiaca concern O. pelinaea and O. parosica; mention of O. mesaritica concerns occasional hybrids between O. iricolor and O. parosica. A list of 31 species and 34 distribution maps, based on previous localizable records, published or not, and on the presence in March 2008 in 44 utmwgs84 squares of 1 km x 1 km, are provided as well as a list of 56 sites prospected during the spring 2008, from March 15 to March 28.Key-Words: Flora of Greece, flora of East Aegean, flora of Ikaria; Orchidaceae, Ophrys basilissa, Ophrys cinereophila, Ophrys icariensis, Ophrys parosica var. parosica, Ophrys pelinaea, Ophrys sitiaca s. str.