Undertaking research studies in the field of mental health is essential in mental health nursing. Qualitative research methodologies enable human experiences to become visible and recognize the importance of lived experiences. This paper argues that involving people with schizophrenia in research is critical to promote their health and well-being. The quality of qualitative research needs scrutinizing according to methodological issues such as trustworthiness and ethical standards that are a fundamental part of qualitative research and nursing curricula. The aim of this study was to critically review recent qualitative studies involving people with severe and persistent mental illness such as schizophrenia and other psychotic conditions, regarding descriptions of ethical and methodological issues in data collection and analysis. A search for relevant papers was conducted in three electronic databases, in December 2016. Fifteen qualitative interview studies were included and reviewed regarding methodological issues related to ethics, and data collection and analysis. The results revealed insufficient descriptions of methodology regarding ethical considerations and issues related to recruitment and sampling in qualitative interview studies with individuals with severe mental illness, putting trustworthiness at risk despite detailed descriptions of data analysis. Knowledge from the perspective of individuals with their own experience of mental illness is essential. Issues regarding sampling and trustworthiness in qualitative studies involving people with severe mental illness are vital to counteract the stigmatization of mental illness.