To reveal probability of epilepsy development (ED) in children estimating various risk factors (relative risks (RR)) concomitant to first seizure episode (FSE). In a prospective study, 267 children with FSE, aged from 2 months to 18 years, were included. We analyzed characteristics of the first seizure, perinatal history, family history of seizures, neurological examination. The patients underwent EEG and neuroimaging [Magnetic Resonance Imaging (MRI) and/or Computed Tomography (CT)]. Children were followed for 3 years from the time of their FSE. The seizure repeated within 3 years in 84.2% (n=225) cases, the rest were single. RR of ED in children with first seizure at the age of 0–12 months was 3.6 (95%CI 1.6–8.4; p=0.003) and at the age of 12–36 months was 0.5 (95%CI 0.3–0.8; p=0.004). RR of ED was 0.6 (95%CI 0.4–0.9; p=0.007) in focal with secondary generalization FSE cases, 15.4 (95% CI 1.0–243.6; p=0.05) in myoclonic seizures cases and 0.4 (95% CI 0.3–0.6; p <0.0001) in patients with generalized tonic-clonic seizures. RR of ED was 4.0 (95%CI 1.3–12.1; p=0.01) in cases with focal neurological symptoms and 0.5 (95% CI 0.3–0.9; p=0.009) in patients with normal neurological status. In cases when epileptiform EEG activity or atrophic and subatrophic changes on MRI/CT were present RR of ED was 1.6 (95%CI 1.0–2.4; p=0.03) and 1.9 (95%CI 1.1–3.1; p=0.01) correspondingly. Risk of ED is higher when FSE occurs at the age of 0–12 months, has myoclonic type, is associated with focal neurological symptoms, epileptiform activity in EEG, brain atrophic and subatrophic changes in MRI/CT.