Introduction: The best and  preferred type of nutrition for babies has been proud to be breast feeding . In spite of  the critical importance of breastfeeding and many national programs performed in this field , some studies conducted in recent years have indicated the mothers' dysfunction . Based on the fact that this is suggestive of mothers' attitude , we evaluated the  mothers' knowledge and attitude towards exclusive breast feeding in Sari in 1386.

Materials and Methods: This was a descriptive cross  sectional study and the subjects  were nursing mothers in Sari. The sampling method  chosen was simple randomized and the data were collected , using a questionnaire including three parts: demographic data, and questions about  the mothers' knowledge and attitude toward breast feeding. Data analysis was done using SPSS13 and chi-square r statistical tests.

Results: Totally, 410 mothers entered this study, with an age range 25.92± 4.90 . Most of them (74.3%) were in low socioeconomic status. More than half of them were uneducated. 52.9 % of them had their prenatal care under observation of a gynecologist. 36.7%  of them had desirable knowledge about breastfeeding while 57.3% had a medium and 6.3% had a low level knowledge about it. 7.1% of the mothers had relatively negative attitude, 68.6% relatively positive attitude and 24.3% had absolute positive attitude regarding exclusive breast-feeding .

Conclusion:  According  to the results , the Mothers' knowledge and attitude towards breast feeding was undesirable (in medium level) .Therefor, there is an urgent need to educate mothers about breastfeeding.