Dear Bioconductor: I appologize for posting my read.table querry prematurely. With a bit more trial and error, the solution to reading a *.csv file from an external drive is: data <- read.table("/Volumes/Drive/Folder/dataset.csv", ...... ) You need to include the /Volumes in the path and use single forward slashes "/' to separate the elements in the path. Cheers, John