The magnitude of mental health problems is considerable. Studies have shown that there is a negative attitude towards mental illness among medical professionals both in mental health services and other health services as well as general population .Such negative attitudes can have detrimental effect on the mentally ill person's ability to find access to services, level of support they receive, type of treatment, development of effective care, and hence their recovery rate. This study aimed to assess the level of nurses' knowledge and to determine their attitudes towards mental illness in mental health and general hospitals .This study followed a descriptive design. The study was carried out at ''Tanta Mental Health Hospital '', '' Psychiatric department of Tanta University Hospital ''and '' Tanta University Students' Hospital. The subjects of the study consisted of 280 nurses working in the previous hospitals .Two tools were used to collect data for the study: first, the questionnaire sheet concerning knowledge about mental illness and second, the community Attitudes towards Mental Illness scale (CAMI). The results revealed, a significant difference between nurses working in mental health hospital and nurses working in general hospital regarding their knowledge and attitudes towards mental illness. Nurses working in mental health hospital had a better knowledge and more positive attitudes than those working in general hospital. The study recommended that, In-service training and educational program for all nurses should be implemented to provide better understanding about the nature of mental illness. Strategies in nursing education should concentrate on the affective domain and communication skills to enhance attitude shaping.