Rotavirus is one of the most common causes of severe life-threatening diarrhoea in children leading to hospitalization especially in developing countries. At Mahosot Hospital in Vientiane, Lao PDR, children with diarrhoea underwent standard clinical evaluation and faecal specimen collection to estimate the burden of rotavirus hospitalizations and to determine rotavirus strain patterns among children aged less than 5 years old. From March 2005 to February 2007, a total of 1158 stool specimens were collected from children aged less than 5 years old hospitalized with acute diarrhoea. Rotavirus was identified in 624 (54%) of these patients. The G1P[8] strain was the most common genotype (35%), followed by G9P[8] (25%). These surveillance data suggest that improved prevention and control programs for rotavirus as well as other causes of diarrhoea are needed in Lao PDR.