I am working on gene expression data from Affymetrix U133 Plus 2.0 array. I have two groups and have run t-tests between groups to identify differentially expressed genes. I have used the following parameters: p-value threshold of 0.01, adjusted Bonferroni correction, 1000 permutations and Welch approximation When I look at the p-values for significant genes, both raw and adjusted p-values are 0 for all significant genes. What does this mean and how do I get the p-values ? It was suggested that I should have these p-values in my Table of significant genes.