The Human breast milk is a dynamic physiological fluid, which contains different living cells. The nutritional constituents of this fluid make it desirable and ideal for new born babies and infants. Possible microbial contamination of expressed human breast milk was observed from this research, and was more likely owing to its rich composition nutritionally. The aim of this study was to examined the presence of bacterial contaminants present in expressed breast milk sample. Sixty (60) breast milk samples were collected from different nursing mothers attending five (5) different Health facilities at Umuahia Metropolis in Abia State for post-natal care. Ten millilitres (10ml) of breast milk was manually extracted from the nursing mothers into universal bottles and transported immediately to the laboratory for analysis. Questionnaires and consent forms where administered to nursing mothers prior to sample collection. Specimens were aseptically cultured on dried plates of blood agar, chocolate agar and later incubated overnight. Isolates were identified by standard microbiological techniques. Bacterial growth was recorded more in samples collected from urban (55%) and educated (48%) mothers than those from rural (25%) and non-educated (35%) nursing mothers studied respectively (p<0.05). Isolates recovered included Escherichia coli 18 (25%), Staphylococcus aureus 17 (24%), Enterococcus faecalis 7 (10%), Streptococcus species 11 (16%), Micrococcus species 6 (9%) and Lactobacillus species 11(16%). Direct breast feeding was rarely practised among participants as only a few urban mothers (10%) neither expressed nor stored breast milk compared to rural mothers (p>0.05). The findings of this study revealed that the nutritional constituent of human breast milk varies at different ages, environment, maternal diets and stages of lactation of the nursing mothers with bacterial contamination observed for most collected samples. Nursing mothers are advised to always practise good personal hygiene in order to minimise possible contamination of expressed breast milk.