This study examines the morpho- syntactic influence of the Ethnic Community Languages (ECLs) in learning Kiswahili as a second language (L2) since little is still known on how L1’s structure affects the acquisition of L2 morpho-syntactically. In this regard Nyakyusa language spoken in Mbeya was taken as a case to represent other ECLs in Tanzania, which are Bantu in origin. The study was conducted in Rungwe district where Nyakyusa natives are dominant. Word lists, questionnaires, interviews and participant observation were the research techniques used in collecting data. The study was descriptive and it employed the Contrastive Analysis Hypothesis as the theoretical framework. The findings revealed that, Morpho-syntactically, both Nyakyusa and Kiswahili follow SVO word order, have noun-verb agreement and are similar in changing from singular into plural. These kinds of similarities positively, influence learners in the process of learning Kiswahili as a second language.