Adverse drug reactions (ADRs) represent a major health care problem. To identify the most common ADRs, drugs implicated in ADRs, and to assess their causality, severity, preventability and risk factors predisposing to reported ADRs in Jordan. Al-Karak teaching hospital, southern of Jordan. Method A cross sectional observational study was carried out for 11 months from January to November 2013. Suspected ADRs were recorded in ADRs report forms and analyzed for causality, severity, and preventability. Most common ADRs, drugs involved in these ADRs, causality, severity, and preventability of suspected ADRs. A total of 64 reports were received. Some patients suffered more than one ADR. The total number of ADRs identified was 108. Forty one drugs were involved in causing these ADRs. About 2/3 of adverse reactions (73.4 %) did not cause admission to the hospital, whereas 26.6 % of the ADRs resulted in admission. Majority of the ADRs were type A (62.5 %). Most of ADRs (92.2 %) were assessed as probable. Nearly, 65.6 % of ADRs were categorized as mild. Majority of ADRs were assessed as "not preventable" (75 %). The most common classes of drugs involved in ADRs were antibiotics, analgesics, vaccines and antiepileptics. The most commonly identified ADRs were abdominal pain, skin rash, shortness of breath, fever, upper gastrointestinal bleeding and vomiting. Risk factors contributed to ADRs were age and polypharmacy. Jordanian healthcare providers should be aware of the importance of detecting and reporting ADRs, in order to prevent and reduce the incidence of ADRs. Awareness of risk factors predisposing to ADRs may help in identifying patients with higher risk and therefore reducing the risk of these ADRs and improving patient outcome.