Our study is the first investigation of proteome of oleaginous yeast Rhotodorula toruloides during conversion of xylose into lipids. We performed comparative proteomics of R. toruloides during cultivation of two carbon sources: glucose and xylose. Proteome analysis revealed significantly lower levels of ribosomal proteins and translation associated factors in xylose-grown cells as compared to glucose-grown cells. We showed that proteins involved in sugar transport, phospholipid and leucine biosynthesis as well as peroxisomal beta-oxidation and oxidative stress response were differentially regulated in response to carbon source.