Background: Sulfone syndrome has been reported in patients treated with sulfur containing agents such as dapsone and carbamazepine for almost a century. But not much as being discuss about it in recent literature. I present a case of sulfone syndrome which occurred. Clinical Case: I present the rare case of a 76-year-old female with rheumatoid arthritis who two weeks after starting sulfasalazine developed systemic symptoms of fever with chills and rigors, headache, and maculopapular skin rash. She had severe mixed picture deranged hepatic function (Hepatocellular and cholestatic picture) and pancytopenia. Microbiological investigations revealed no microbial etiology. The patient was treated with prednisolone and supportive therapy including discontinuation of the sulfasalazine. Her symptoms improved and resolved within 5 days. The pancytopenia resolved in a week and liver function test gradually improved and normalized by 90 days. Conclusion: Although sulfone syndrome can resolve once the offending sulfur agent is discontinued it can cause severe morbidity and mortality. Therefore. I urge physician starting patients on sulfur containing agents such as sulfasalazine to always watch out for sulfone syndrome as a possible adverse reaction.