Strains of host specific (KTM, 74/1, and 59) and nonhost specific (40) lactobacilli were orally dosed to day-old broiler chicks. Dose levels consisted of: 5.0, 7.0, and 9.0 log10 cfu/day for 21 days. Each treatment and control group (placebo, no culture) contained three replications of 6 chicks in Experiment 1 (strains 40 and KTM) and 7 chicks in Experiment 2 (strains 74/1 and 59). Dosing of 7.0 log10 cfu and above tended to depress chick growth. Fecal shedding of lactobacilli were the same (8.8 log10 cfu) for all dose levels on Day 5 but decreased on Day 14 for strains KTM and 40. For strains 74/1 and 59 at all dose levels, the fecal shedding of lactobacilli was 9.9 log10 cfu for Day 5 and 8.5 log10 cfu for Day 14. Microbiology was performed on contents of the crop and ileum and on the tissue macerates from the crop, ileum, and ceca from chicks killed on Days 7 and 21 of the experiments. Chicks dosed with strains 59 and KTM had lower numbers of coliforms in cecal macerates than the control and chicks dosed with strains 40 and 74/1. No significant differences were observed in lactobacilli found in contents and tissues between 5.0 and 9.0 log10 cfu for all lactobacilli strains dosed. There was a trend for the liver biotin to be higher in chicks dosed with 7.0 log10 cfu than chicks dosed with 5.0 or 9.0 log10 cfu or no culture, but the difference was not significant (P greater than .05).