Background Childhood unintentional injuries are unexpected occurrences affecting a child, which lead to immeasurable grief and suffering to entire family. It is one of the leading causes of hospitalisation among children in Sri Lanka resulting death and disability. Children aged 1–4 years are at greater risk of unintentional injuries and majority of injuries among this age group occur in their family environment. Prevention of such injuries requires a clear understanding of their contributory factors.

Methods A community based descriptive cross sectional study was carried out among children aged 1–4 years residing in an urban setting of Sri Lanka, to assess the incidence and associated family related factors of unintentional injuries. 458 children were recruited using simple random sampling technique, giving a response rate of 91.6%. Parents of selected children completed an interviewer administered questionnaire (IAQ) that recorded the parent’s recollection of their child having an unintentional injury needed medical attention, within three months prior to the interview. Socio demographic factors and family related factors of the study subjects were also collected by the IAQ. The data was analysed using SPSS 18.2 statistical package.

Results The incidence of unintentional injuries during the study period of three months was 28.1 per 100 children (95% CI = 19.46–36.74).

The factors that were significantly associated with the occurrence of unintentional injuries among children are low monthly income of the family (p = 0.045), low social support to the mother of index child (p = 0.022), non authoritative type of parenting of the mother of index child (p = 0.039), cared by person other than mother during day time (p = 0.002), frequent arguments between parents (p = 0.004) and frequent alcohol consumption of father (p = 0.001).

Conclusions Unintentional injuries are an important child health issue among children aged 1–4 years. Identification of family related contributory factors for unintentional injuries among this age group will enable policy makers to formulate effective child injury preventive interventions.