Introduction: Breastfeeding is a diet for children with their mother's milk which achieves nutritional, psychosocial, imunological, practical and economic aspects of the child's and mother's health and a stable emotional and cognitive development of the child. Objective: Determine the level and significance of the influence of some sociodemographic and psychobiological factors to breastfeeding and duration of breastfeeding with examinees from Zadar county. Examinees and procedures: 155 examinees participated in the research in Zadar county. The poll questionairre examined the influence of some sociodemographic and psychobiological factors on choosing breastfeeding and duration of breastfeeding. The data was statistically processed. Results: The examinees were on average 31 years old, mostly married, employed, good economic status and living in their own families. The age of the examinees and consumation of tobbaco products are significant predictors of duration of breastfeeding. The level of education of the examinees and previous experience in breastfeeding show a tendency of significance,while economic status, time of decision to start breastfeeding, consumation of alcohol and attending maternity classes have no statistically significant predictive value. The examinees partners as well as their mothers have the greatest influence and support the examinees to breastfeed. The average duration of breastfeeding amongst the examinees was 4,2 months and at 9,5 months adapted milk was introduced into the babies nutrition. Conclusion: Different factors influence the decision of mothers on breastfeeding and the length of breastfeeding. The age of the examinees and consumation of tobacco products show a clear statistical significance, educational status and parity of mothers a tendency of significance while economic status, timing of decision on breastfeeding, attending maternity classes do not influence the duration of breastfeeding despite different expectations. The mothers in the Zadar county apply exclusively short breastfeeding and start early with introducing supplements to breastfeeding in relation to recommendations by the WHO.