Aim: To analyze the biochemical profile of complications in patients exhibiting acute febrile illness. Material and methods: This hospital-based prospective observational study was conducted in the Department of Medicine.100 Patients age more than 13 yrs. who presented with complaints of fever with complications admitted to emergency department orgeneral wards ICU, and were ready to give consent are enrolled for study. Patients whose complaints and lab profile do not match with acute fibril illness were excluded, thorough details of history Details of history and results of a were taken and enter was made onstandard sheet. Results: Upon admission, the biochemical profile showed a mean hemoglobin level of 12.5 g/dL (±1.8), a total leukocyte count of 12,000 cells/mm³ (±3500), and a platelet count of 150,000 cells/mm³ (±50,000). The average serum creatinine level was 1.2 mg/dL (±0.4), while liver function tests indicated elevated ALT (40 U/L ± 15) and AST (35 U/L ± 10). Bilirubin levels were within normal limits, with a total of 1.0 mg/dL (±0.3) and direct bilirubin at 0.5 mg/dL (±0.2).Comparison between survivors (n=85) and non-survivors (n=15) highlighted significant differences in biochemical parameters. Survivors generally exhibited higher hemoglobin levels (12.8 g/dL ± 1.6) compared to non-survivors (10.5 g/dL ± 1.2). Likewise, survivors had lower total leukocyte counts (11,000 cells/mm³ ± 3000) and higher platelet counts (160,000 cells/mm³ ± 45,000) compared to non-survivors (18,000 cells/mm³ ± 5000 and 90,000 cells/mm³ ± 30,000, respectively). Serum creatinine levels were lower in survivors (1.1 mg/dL ± 0.3) compared to non-survivors (2.0 mg/dL ± 0.5). Liver function markers ALT and AST were also notably lower in survivors (35 U/L ± 10 and 30 U/L ± 8, respectively) compared to non-survivors (45 U/L ± 12 and 50 U/L ± 15). Bilirubin levels showed similar trends, with lower total (0.9 mg/dL ± 0.2) and direct (0.4 mg/dL ± 0.1) levels in survivors compared to non-survivors (1.5 mg/dL ± 0.4 and 0.8 mg/dL ± 0.2, respectively). Conclusion: This study presents a comparative analysis of the biochemical clinical profile of infectious diseases that occur after the monsoon and in early winter. It aims to enhance physicians' understanding of the complication profile and outcomes associated with these diseases. The findings of this study can play a significant role in reducing mortality and morbidity by facilitating early referral to a tertiary center and prompt management of the disease and its potential complications.