An in ovo trial was carried out to investigate the effect of injecting Lactobacillus acidophilus to 18 days old chicken embryo on the production performance of commercial broilers. 720 broiler hatching eggs (Cobb-400) with uniform weight were randomly selected, divided in to 5 groups with 6 replicates of 24 eggs each and incubated under standard conditions. In ovo injection was carried out on 18th day of incubation, out of total 720 eggs, 144 eggs served as non injected control (T1), 144 eggs served as sham control and the remaining 432 eggs (144 for each treatment group) were injected with 0.2 ml of 1x106 Lactobacillus acidophilus (T3), 0.2 ml of 1x109 Lactobacillus acidophilus (T4) and 0.2ml of 1x1012 Lactobacillus acidophilus (T5). The positive control group was injected with 0.2 ml of 0.9% normal saline solution. At hatch, 480 chicks were randomly selected (96 birds in each treatment) with six replicates of 16 birds each as per treatment wise. Data on hatchability, chick weight, body weight, weight gain, feed consumption, FCR and livability were recorded and subjected to statistical analysis. There was no significant difference in per cent hatchability among treatment and control groups. The body weight and weight gain were significantly (P<0.01) affected by in ovo injection of Lactobacillus acidophilus irrespective of concentration on 2nd, 4th and 6th week of age. The feed consumption was significantly (P<0.01) higher in probiotic injected groups compared to negative and sham control only on second week. The biweekly cumulative FCR was significantly improved by in ovo infusion of probiotics during 2nd and 4th week whereas 6th week FCR was not affected. The livability was significantly (P<0.05) higher in probiotic infused groups. Based on the results of the present study it can be concluded that the in ovo injection of Lactobacillus acidophilus has got beneficial effect on the growth performance and survivability of commercial broilers.