The study aims are to assess the knowledge of nursing student regarding bill of right of mentally ill patient and to identify the relationship between the knowledge level and socio demographic variables of nursing students. The quantitative research approach and cross sectional descriptive design was adopted for the study. The study was conducted in Narayana Nursing institution. 30 nursing students were selected by using Non Probability Convenience Sampling Technique. Self-structured Questionnaire method was used for collecting the information from samples. Data analysis done by using descriptive and inferential statistics. The results revealed that 19 (63.34%) nursing students have inadequate knowledge, 7(23.3%) nursing students have moderately adequate knowledge and only 4(13.33%) nursing students have adequate knowledge regarding bill of right of mentally ill patient. The study concluded that majority of nursing students has inadequate knowledge and socio demographic variables have shown non-significant association with the level of knowledge.