The prevalence of antibiotic resistant bacteria causing neonatal diarrhoea in calves has become a serious problem in the control of infection. Due to increasing antibiotic resistance, the bacteriophages with probiotics are considered the best alternative. The aim of study was to evaluate the using a suppository with probiotic strains of Lactobacillus spp. and bacteriophages specific for pathogenic E. coli in young calves with diarrhoea. The study evaluated therapeutic and prophylactic effects. The study was carried out on 24 female HF calves, aged 2 to 7 days and weighing from 35-46 kg. The calves were divided into four groups (n=6) each: Group 1 – healthy control, received no medicine; Group 2 – positive control with diarrhoea; Group 3 – healthy calves received medicine; Group 4 – calves with diarrhoea received medicine.The animals received suppositories with Lactobacillus spp. and bacteriophages specific for pathogenic E. coli for five days. On the first day, calves received the suppositories twice– in the morning and 12 hours later; subsequently they were administered once a day. The health status of calves was observed for 11d after the first application of suppositories. A protective and preventive effect of the experimental therapy was obtained in the research. The probiotic-phage suppositories reduced the duration of diarrhoea in calves, completely eliminating it within 24-48 hours after application The used therapy stimulated the activation of immune mechanisms in calves, which translated into an enhanced specific and non-specific response and increased resistance to infection.