Thirty cases of tropical myositis, (22 suppurative, 8 non-suppurative) aged 11 to 65 years were seen in a period of one year. There were 22 males and 8 females. There was a total of 78 muscular lesions in 22 suppurative cases and 19 muscular lesions in 8 non-suppurative cases. The most common presentation was localised myalgia (100%), fever (96.7%) generalized myalgia (56.7%), arthralgia (40%), pain in abdomen (33.3%) and breathlessness (30%). Extramuscular complications were present in 50% cases. Twenty four muscle biopsies were taken. Sixteen showed changes of suppurative myositis i.e. non-specific acute inflammatory reaction, muscle necrosis with myocytolysis, vacuolation of cytoplasm and loss of striations. Cell mediated immunity was found to be suppressed in patients of non-suppurative myositis in comparison with the suppurative group. IgG, IgA and IgM were significantly raised in patients in comparison to controls (p less than 0.05). The intact humoral immunity indicates good response to acute phase reaction and increased levels of IgG, IgA and IgM (specially IgG) can be taken as good prognostic parameter.