Abstract: Aim of the study: Many studies from various parts of India have reported scrub typhus with diagnosis based on IgM ELISA; however no definite data available for IgM for Scrub Typhus as prognostic indication .Our study gives a correlation of IgM level with the clinical presentations as well as organ involvement and complications thus depicting the prognostication. Material and methods: - This descriptive observational investigation was carried out over a time of two years. Hospitalized cases with complaints of Indistinct febrile disease with a lymphadenopathy, organomegaly as well as head pain were taken over a period of five days deprived of a recognizable cause. as probable scrub typhus patients and advised for initial Weil- Felix test and scrub IgM level. The spectrum of clinical manifestation and end organ damage were analyzed with scrub typhus serum IgM level. Results:Among 113 patients diagnosed as scrub typhus basing on IgM value, 48 are children (below 14 yrs) and 65 are adults. Mean age of presentation in children is 3.6 Yrs and adult is 41.5 yrs. Maximum no 43 (26.27%)of patients have IgM value between 2.5 to 3.5 and only five patients have very high value i.e. more than 3.5 . There is significant correlation (P= 0.0027) of presence of clinical and lab finding like rash, eschar, lymphadenopathy, leukocytosis, thrombocytopenia with increasing value of IgM. Among 113 cases, majority had hepatopathy 56(49.5%) followed by nephropathy and sepsis (23.9% each). Only five no of patients have cardiac complications. The percentage of distribution of end organ complications is increasing (P= 0.048) with increasing IgM value except cardiac illness, where the burden is very negligible. Conclusions: The prognostic indicator of severe disease can be established with increasing trend of serum IgM level with available evidence but a larger study with paired sera will ascertain the correlation..