To determine the seroprevalence of leptospirosis among febrile inpatient cases in northeastern Malaysia.A hospital-based cross-sectional study was conducted among 999 febrile cases admitted to 10 hospitals in northeastern Malaysia. A survey using a proforma sheet was used to obtain sociodemographic and occupational information. Serum samples were screened for leptospirosis by IgM enzyme-linked immunosorbent assay test (IgM ELISA) and confirmed by microscopic agglutination test (MAT).There was an equivalent distribution of males and females in the 999 respondents enrolled in the study. The majority were Malay (94.7%) and their mean age was 39.4 (standard deviation 17.6) years. The overall seroprevalence of leptospirosis was 8.4% (95% confidence interval (CI) 6.8-10.3) (n=84). The high-risk occupational group was found to have a higher seroprevalence, which was 56% (95% CI 45.3-66.1) (n=47). The predominant serogroup was Sejroe (82.1%, 95% CI 72.6-88.8) (n=69).This study revealed a possible high seroprevalence of leptospirosis among febrile cases, indicating the need to review the importance of adding leptospirosis to the case investigation of febrile illness, especially among high-risk occupational groups in Malaysia, as well as in other endemic countries.