Hi all, Thanks to Dick Beyer we have uncovered a bug that affects justRMA and justGCRMA. It appears to alter the ordering of the results returned. This only affects the devel versions of affy (1.4.22), and gcrma (1.0.6), so for now I would recommend not using these two functions. I will let you all know when the bug has been sorted out and the corrected versions posted. Best, Jim James W. MacDonald Affymetrix and cDNA Microarray Core University of Michigan Cancer Center 1500 E. Medical Center Drive 7410 CCGC Ann Arbor MI 48109 734-647-5623