Background Postoperative nausea and vomiting (PONV) and postoperative pain (POP) are most commonly experienced in the early hours after surgery. Many studies have reported high rates of PONV and POP, and have identified factors that could predict the development of these complications. This study aimed to evaluate the relationship between PONV and POP, and to identify some factors associated with these symptoms. Methods This was a prospective, multicentre, observational study performed at An-Najah National University Hospital and Rafidia Governmental Hospital, the major surgical hospitals in northern Palestine, from October 2019 to February 2020. A data collection form, adapted from multiple previous studies, was used to evaluate factors associated with PONV and POP in patients undergoing elective surgery. Patients were interviewed during the first 24 h following surgery. Multiple binary logistic regression was applied to determine factors that were significantly associated with the occurrence of PONV. Results Of the 211 patients included, nausea occurred in 43.1%, vomiting in 17.5%, and PONV in 45.5%. Multiple binary logistic regression analysis, using PONV as a dependent variable, showed that only patients with a history of PONV [odds ratio (OR) = 2.28; 95% confidence interval (CI) = 1.03–5.01; p = 0.041] and POP (OR = 2.41; 95% CI = 1.17–4.97; p = 0.018) were significantly associated with the occurrence of PONV. Most participants (74.4%) reported experiencing pain at some point during the first 24 h following surgery. Additionally, the type and duration of surgery were significantly associated with POP (p-values were 0.002 and 0.006, respectively). Conclusions PONV and POP are common complications in our surgical patients. Factors associated with PONV include a prior history of PONV and POP. Patients at risk should be identified, the proper formulation of PONV protocols should be considered, and appropriate management plans should be implemented to improve patients’ outcomes.