Hi Tom You can use the nuID2IlluminaID function to convert nuID back to Illumina ID. You can also have a quick check of the featureData, it's very possible the original Illumina ID and other annotation information are there: head(fData(lumiBatch)) Pan Date: Thu, 15 Dec 2011 13:43:18 +0000 From: "Thomas H. Hampton" <thomas.h.hampton@dartmouth.edu> To: Bioconductor mailing list <bioconductor at="" stat.math.ethz.ch=""> Subject: [BioC] Extracting PROBE_ID from lumiBatch Message-ID: <65DF8E95-6BBC-42FA-B669-B0B22CD6487D at Dartmouth.edu> Content-Type: text/plain; charset="us-ascii" The default featureName created by lumiR is a nuID. Is there some way to extract corresponding Illumina probe ids from a lumi batch? Thanks very much. Tom