Background. The incidence of sepsis among newborns ranges from 1–12 to 38 per 1,000 live births in the world according to scientific literature [1, 2]. The clinical case demonstrates the features of the newborn organism sensitivity and the therapeutic and diagnostic process difficulties. Clinical case description. The boy was born on the 37th week of gestation, 1st of twins, with body weight 3330 g, height 51 cm, APGAR score 8/9 points.He was on breastfeeding. His condition has deteriorated rapidly on the 9th day of life. The condition was severe due to intoxication syndrome, necrotising enterocolitis (NEC) manifestation, further development of systemic inflammatory response syndrome and multiple organ dysfunction syndrome. Severe pain syndrome and movement restraint in limbs have appeared on the 20th day of life. X-ray imaging: NEC signs, multiple osteomyelitis foci in the limbs.Conclusion. Modern adequate diagnosis and justified treatment tactics have led to positive outcome: child’s condition has improved, body weight has increased, pain syndrome has been managed, the volume of movements in the limbs has increased, inflammatory markers have stabilised. The child was discharged from hospital in satisfactory condition at the age of 2 months.