This study was designed to evaluate the role of Salmonella enterica serovar Typhimurium as a causative pathogen in hospitalized diarrhoeal patients younger than five years old, extract and purify endotoxin (lipopolysaccharide; LPS) from isolated and identified S. Typhimurium, and determine the histological activity of LPS-liposome conjugate in liver and spleen section of albino mice male. The patients (95 cases) were admitted to the Central Pediatric Hospital and Al-Kadhiymiah Pediatric Hospital in Baghdad during the period 24/10/2010 - 30/11/2010, because of severe diarrhoea and fever. Bacterial evaluation of stool samples revealed the identification of two (2.1%) S. Typhimurium isolates (S1 and S2). Antibiotic sensitivity test demonstrated that S1 isolate was more resistance than S2 isolate; therefore it was considered more virulent and subjected for extraction and purification of LPS. Chemical characterization of the extracted LPS revealed that the carbohydrate content was 2.34 mg/ml, while the protein concentration was very low (0.52 ?g/ml). Partial purification of extracted LPS by using gel-filtration chromatography (Sephacryl 200 S) showed three peaks, and after determination of protein and carbohydrate concentrations for each peak, peak two was observed to have the highest carbohydrate content (25%) and the lowest contaminated protein (0.001%). The LPS of this peak was histologically evaluated in mice at a concentration of 100 ?g/ml, alone or in conjugation with a commercially available liposome (LIP). These evaluations revealed that LPS-LIP conjugate was showed in histological section of liver look like normal especially near portal area.