Globally, small and medium size enterprises (SMEs) are being hailed for their pivotal role in promoting grassroots economic growth and equitable sustainable development. It is estimated that SMEs constitute over 90 percent of total enterprises in most economies with a high rate of employment growth. They are also a vehicle for increased industrial production and export. The study was guided by the following objectives (i) to find out the contribution of SIDO to SMEs in terms of: (a) training and consultancy services (b) technology and technical support; (ii); to find out contribution of SIDO to SMEs in terms of;- (a) Development and improvement of market and information services (b) Improvement and expansion of financial advisory and credit services (ii) To find out others strategies to be employed in order to improve the performance of SMEs in Nyamangana district. The research employed quantitative approach. And survey involved interview of 95 respondents by a using questionnaire and interviews. Data were analyzed using the SPSS package and content analytical tools. The findings of the study reveals that more than 60% of SME’s in Nyamagana agreed that they were getting training, technological support, market information, financial advisory and credit services. Further the research revealed that other SMEs were neutral to indicate their opinion. This implies that they are maybe not getting training, technological support, market information, and financial advisory and credit services. The study recommends that, [since the research findings revealed that about 40% of the SME’s in Nyamagana were neutral to tell whether they were getting adequate training, technological and technical support, market and information services,] financial advisory and credit services, SIDO should put more efforts in providing these services to the SMEs. This study identified other areas for further research. Research should be conducted to find out the contribution of other organizations to the development of SME’s. There is also a need to conduct extensive survey in other cities in Tanzania such as Dar es Salaam, Dodoma, Arusha, and Zanzibar to generalize the results to the entire population.