Background: Patients with psychotic disorders especially those have delusions show a greater level of non-adherence to prescribed psychiatric medication. Aim: aimed to explore the relation between conviction, preoccupation of delusion and adherence to medication among psychotic clients. Subjects and Method: A descriptive correlational research design was operated. 110 psychotic patients suffering from delusional beliefs recruited from psychiatric outpatient clinics at Port Said and Demira Mental Health Hospital. A structured Interview Schedule for the valuation of Delusional Beliefs, the Conviction of Delusional Beliefs Scale, and Drug Attitude Inventory Scale, in addition to personal and clinical data questionnaire. Results: The majority of the studied patients didn't adhere to the medication. Also, the majority of studied patients had moderate degrees of conviction and preoccupation of delusional beliefs. Conclusion: there was a statistically significant positive correlation between preoccupation and conviction of delusional beliefs. Whereas, there were statistically significant adverse correlations between. Conviction, preoccupation of delusional beliefs and adherence to medication amid the studied psychotic clients. The main recommendation was implementation of cognitive behavioral therapeutic approaches to modify delusional preoccupation and conviction among psychotic patients. These approaches should be led by health professionals as psychologists and psychiatric nurses.