Objective:Pulmonary haemorrhage is an increasing cause of death in leptospirosis patients.However,molecular mechanism underlying pathologies in this organ is not clearly understood.It has been shown that sodium transport was disturbed following Leptospira infection.LipL21 is the second abundant outer membrane protein found only in pathogenic Leptospira.Its expression in vivo has been shown which suggests that this protein may be involved in survival in hosts or pathogenesis.However,the expression of this protein in host organs and its role in lung pathology has not been demonstrated.In this study we demonstrated the expression of LipL21 in lungs of hamsters infected with pathogenic Leptospira.Methods:Lung tissues were collected from Golden Syrian hamsters injected with Leptospira interrogans serovar Pyrogenes at days 3,5 and 7 post-infection.Four hamsters were used for each time point.Lungs from non-infected hamsters were collected as a control group.LipL21 mRNA expression in lung tissues was investigated by reverse transcription and nested PCR.Results:LipL21 mRNA expression was detected in all lung tissues from hamsters infected with pathogenic Leptospira.No PCR product was detected when tissues from non-infected hamsters were investigated.Conclusion:Our data demonstrated that LipL21 is expressed in lungs of hamsters infected with pathogenic Leptospira.Additional experiments such as quantitation and localization of LipL21 expression in lungs will provide further information whether this protein is involved in pathogenesis. Objective: Pulmonary haemorrhage is an increasing cause of death in leptospirosis patients. Despite the molecular mechanism underlying pathologies in this organ is not known. It has been shown that sodium transport was disturbed in the following Leptospira infection. LipL21 is the second abundant outer membrane protein found only in pathogenic Leptospira .Its expression in vivo has been shown that suggests that this protein may be involved in survival in hosts or pathogenesis. However, the expression of this protein in host organs and its role in lung pathology has not been likely. study we demonstrated the expression of LipL21 in lungs of hamsters infected with pathogenic Leptospira. Methods: Lung tissues were collected for Golden Syrian hamsters injected with Leptospira interrogans serovar Pyrogenes at days 3,5 and 7 post-infection. Flow hamsters were used for each time point.Lungs from non-infected hamsters were collected as a control group. LipL21 mRNA expression in lung tiss ues was investigated by reverse transcription and nested PCR. Results: LipL21 mRNA expression was detected in all lung tissues from hamsters infected with pathogenic Leptospira. No PCR product was detected when tissues from non-infected hamsters were investigated. Confluence: Our data demonstrated that LipL21 is expressed in lungs of hamsters infected with pathogenic Leptospira. Additional rules such as quantitation and localization of LipL21 expression in lungs will provide further information whether this protein is involved in pathogenesis.