Dear all, There seems to be a problem with probe annotation of certain Illumina arrays in biomaRt. The following arrays: HumanWG6_V1, HumanRef8_V1, MouseWG6_V1, MouseWG6_V1_B do not have valid Illumina probe names under the "ProbeId" column. They seem to contain values which are in the column "Array_Address_Id", which is the one next to the Probe_id column in the official Illumina flat files. For example. the array "MouseWG6_V1" library(lumiMouseIDMapping.db) dbconn=lumiMouseIDMapping_dbconn() tableNames=dbListTables(lumiMouseIDMapping_dbconn()) tableNames = tableNames[grep("Mouse",tableNames)] tableNames data = dbReadTable(dbconn,"MouseWG6_V1") head(data) The column ProbeId contains identifier "105290026" which is in the flat file on http://www.switchtoi.com/pdf/Annotation%20Files/Mouse/MouseWG- 6_V1_1_R4_11234304_A.zip under the column Array_Address_Id and has a proper identifier of "ILMN_1229450". Hope this helps and that it might be corrected sometime in the future, Nenad Nenad Bartonicek EMBL- European Bioinfromatics Institute Wellcome Trust Genome Campus Hinxton, Cambridge