Background: The suicide with aluminum phosphide, known as rice tablet, has increased significantly. This study aimed to investigate the epidemiology of Aluminum Phosphide (ALP) poisoning and determine the in-hospital mortality prognostic factors in adult people referring to ALP poisoning to one of the main poisoning centers in southern Iran. Methods: This retrospective cross-sectional study (March 21, 2014, to March 21, 2018) was conducted on all adult patients (>16 years) with ALP poisoning who were referred to Ali-Asghar Hospital (affiliated with Shiraz University of Medical Sciences). All data were extracted from the patients’ medical files. The patients were categorized into two groups of survived and non-survived. Univariate and multivariate logistic regression analyses were conducted to determine prognostic factors for in-hospital mortality, and Odds Ratios (ORs) were reported. Results: Totally, 97 patients were enrolled in this study. The patients’ Mean±SD age was 29.3±12.2 years. Both study groups (survived and non-survived) were matched in most demographic and poisoning characteristics. Nausea (62.9%) and vomiting (49.5%) were the most symptoms at the time of admission. Castor oil (66%), N-acetyl cysteine (56.7%), and magnesium sulfate (52.6%) were the most frequent treatment in these patients. The multivariate analysis showed that age (OR=1.12, 95%CI: 1.03-1.22), body temperature (OR=0.02, 95%CI: 0.01-0.48), resistant acidosis (OR=77.10, 95%CI: 5.05-1176.86), and taking sodium bicarbonate (OR=12.35, 95%CI: 1.25-122.10) were the prognostic factors of in-hospital mortality. Conclusion: The in-hospital mortality rate in patients with ALP poisoning was 29.9%. Age, illiteracy, body temperature, resistant acidosis, and taking sodium bicarbonate were the prognostic factors of in-hospital mortality in these patients.