This paper is on the subject of "The Interference of Echuwabo in the Production of Written Texts in Portuguese Language Classes: The Case of Students in Class 10, Class C, Day Course, at the Eduardo Mondlane General Secondary School, Quelimane City-2018". The problem raised seeks to find out to what extent the Echuwabo language interferes with written production in Portuguese, taking into account that in Mozambique it is the language of instruction and the second language of many Mozambicans. The general objective is to understand the phenomenon within students, in terms of their "writing" skills. In order to carry out the work, we used the bibliographical method and field research, which allowed us to collect data from those surveyed. The ethnographic method, applicable to sociolinguistic studies, was used as the method of approach. As for the approach, the research was mixed, since it merged mathematical and non-mathematical languages. The objectives were descriptive and exploratory. Descriptive because it also describes the characteristics of 10th graders and exploratory because it did not require the formulation of hypotheses to be tested.