The purpose of this study was to examine the contribution of NMB financial services towards the development of SMEs in Tanzania. The study was guided by three specific objectives; namely, to examine the development trend of SMEs in Nyamagana District, to examine the role played by NMB in supporting SMEs development in Nyamagana District, to explore means for improving SMEs sector development in Nyamagana District. The study used descriptive research design and surveyed 122 SME owners/ operators in various business categories and 3 NMB employees. It used self administered questionnaire and interview for selected respondents. The data were analyzed using descriptive statistics with the aid of SPSS. The findings showed that SME owners/ operators were engaged in several business categories; namely, manufacturing services and trade. SME owners /operators first become NMB customers before they qualify to apply for business loans. SME owners/ operators who have obtained loans are able to increase their business performance in terms of sales and number of workers they employ. The study also indicated that majority of SMEs who operated business for a long period perform better in business than those who are new in business. The study recommended that NMB provide higher amounts of loans with low interest rate, give a grace period to new business starters before they start making loan repayment, also trade finance should be addressed to SMEs to reduce transaction costs such as transport cost to SMEs.