Lactobacillus plantarum is commonly used as starter cultures in the manufacturing of dairy and meat products. The objectives of this experiment were to study the effects of oral administration of L. plantarum I-UL4 (LP) in the diet of postweaning rats on growth performance, faecal pH, Enterobacteriaceae and lactic acid bacteria (LAB) counts and plasma cholesterol concentrations. LP was isolated from local food, tempeh. The viable count was 4×10^10 CFU/g of pellet. A total of 24 Sprague-dawley (4 weeks of age) male rats were assigned individually into three groups with 8 rats per treatment. The three dietary treatments were: (i) control diet (basal diet), (ii) basal diet + 2.5% LP and (iii) basal diet + 7.5% LP. The initial weight, final weight, growth rate, total feed intake and feed conversion ratio were not significantly different for all the treatment groups. The addition of LP in the diets reduced the Enterobacteriaceae population in faeces of the rats after two weeks of experiment. The faeces from rats fed LP had significantly (P<0.05) higher numbers of LAB than faeces from the control rats at the last week of experiment. The faecal pH of rats fed with LP was more acidic than those rats fed with basal diet only. The plasma cholesterol concentrations of rats fed with LP were significantly lower than that of control rats. In conclusion, the rats fed 2.5 and 7.5% LP diet had a lower faecal Enterobacteriaceae counts, faecal pH and plasma cholesterol concentration and without any detrimental effect on growth performance of rats.