Background: Few studies have examined the risk factors among Iranians attempting suicide. Objectives: The present study aimed to explore the risk factors of suicide among patients admitted to hospitals due to suicide attempts. Patients and Methods: Suicidal participants (N = 200, 104 males and 96 females, aged 18 to 40) were recruited via judgmental sampling method, and non-suicidal participants (n = 300, 166 males and 134 females, aged from 18 to 40) were selected via a convincing sampling method. The participants completed a battery of questionnaires on family strength, religious identification, substance use, hopelessness, depression, sexual, emotional, and physical abuse, impulsive aggression, neuroticism, suicidal ideation, family discord, stressful life events, and anxiety. Data were analyzed by independent t-test, chi-square and hierarchical logistic regression. Results: The current use of cigarettes/hookah, lifetime non-prescribed medication use, suicidal ideation (suicidal thoughts/tendencies), and depression significantly predicted suicide attempts. In addition, lower levels of religious belief were significantly associated with a higher likelihood of attempting suicide. Conclusions: Suicide prevention programs should explore the efficacy of treating individuals with substance abuse disorders, depression, and suicidal thoughts/tendencies for the reduction of suicide attempts. Furthermore, family, media, and school-based programs to internalize religious values would be valuable components of prevention programs for suicide in Iran.