Breast feeding practice especially exclusive breast feeding (EBF) is a major determinant of child growth and development. In Tanzania, most women breastfeed their infants for long periods, but many introduce alternative feeding too early in life. The objective of this study was to determine factors affecting EBF and the relationship between feeding practices and the nutritional status of infants. This cross-sectional survey, using a semi-structured questionnaire, was conducted in Morogoro Municipality in Tanzania. The study involved lactating women recruited from five randomly selected health facilities. Demographic, clinical, knowledge and practices related to infant feeding as well as infant anthropometric information were collected. Infant nutritional status was assessed based on weight-for-age, height-for-age and weight- for- height. There were wide variations in knowledge and practice of breastfeeding among women. Majority (92%) of the respondents gave colostrums to infants although more than 50% did not know its benefits. Eight percent of the respondents discarded colostrums on the account that it is not good for their neonates. Only 23.1% of the respondents thought that infants should be breastfed exclusively during the first six months of infancy. Ninety–eight percent of infants < 1 month of age received breast milk only, compared with 28.5% of infants aged 2-3 months and 22.3% among those who were above 3 months of age. No child in the ≥4 months old was exclusively breastfed. Over 80% of the infants had normal weights, 13% were stunted and 8% wasted. EBF was associated with higher scores for height- for- age Z ( P <0.05) and weight- for- height Z ( P <0.01). Age, education level and occupation of respondents were important predictors of EBF. Overall, breast feeding practices in the study population were largely suboptimal. As a result, considerable proportions of children had poor health indicators. Thus, correct breastfeeding practices should be supported and promoted to improve the well-being of children.