The oxidation of methionine in peptides is often associated with the loss of biological activity. Since methionine showed good antiinflammatory activity, its oxidized products methionine sulfoxide and methionine sulfone were tested. The sulfone was more active than the sulfoxide although methionine was most active indicating that the antiinflammatory activity is not correlated with the oxidation state of sulphur. their hydroxyl radical scavenging activity was measured. Methionine was most active and sulfone was least active. Here also no correlation with antiinflammatory activity was found. © 1990 Birkhäuser Verlag.