Effect of a potent methylation inhibitor oxidized adenosine (Adox), and a universal methyl group donor S-adenosyl-L-methionine (AdoMet) on trehalose metabolism was studied in two haploids of S. cerevisiae of mating types MATalpha, met3 (6460 -8D) and MATa, leu2, ura3, his4 (8534 -10A). Trehalose level decreased in presence of Adox in both strains. Both neutral trehalase (NT) and trehalose-6-phosphate (tre-6-p) synthase activities increased in presence of Adox in -8D strain. Decrease in trehalose level in -8D thus could not be explained in the light of increased tre-6-p synthase activity; however, it could be correlated with increased NT activity. In strain -10A, NT activity was reduced in presence of Adox while tre-6-p synthase activity increased. Enzyme activity profiles in -10A thus do not explain the reduced trehalose level on Adox treatment. Effect of AdoMet was not very prominent in either strain, though in -8D a small increase in trehalose level was seen on treatment. Intracellular AdoMet level of untreated cells of -10A was seen to be almost six times higher than that of -8D. Further, AdoMet treatment caused increase in its level compared to untreated cells, suggesting AdoMet uptake. No effect of either compound was seen on acid trehalase (AT) activity in any strain. The results suggest that there was a possible effect of demethylation on trehalose metabolism (particularly in the synthetic direction) in both strains, though effect of methylation was not very prominent, the reason for which is not very clear.