until today, the search for numerical accuracy, capable of being validated, confirmed and reproduced, represents the main form of knowledge construction in several areas of social science. while qualitative research has widened its range and gained distinction, its value is questioned by some researchers who believe that it has neither the same rigour in the collection and analysis of data as quantitative research nor capacity for generalization of the results. in this short essay, an attempt is made to discuss two elements of rigour in qualitative research: validity and reflexivity. firstly, a theoretical review is carried out in an effort to define and discuss the concept of validity, as well as highlight the different interpretations given to the term in different epistemological currents. with regard to the concept of reflexivity, the paper highlights the importance of adopting a critical analysis of science with emphasis on the position and actions of the researcher when performing his/her work and the relation that is established with the subjects under study. to finish, some remarks are offered on the construction of knowledge in the scientific field and the role of researcher.