Introduction: Obesity is a major public health concern. Accurate perception of body weight may be critical to the successful adoption of weight loss behavior. The aim of this study was to determine the accuracy of self-perception of BMI class. Methods: Patients admitted to the acute medical service in one regional hospital completed a questionnaire and classified their weight as: “underweight,” “normal,” “overweight,” or “obese.” Reponses were compared to clinically measured BMIs, based on the WHO Classification. Patients were also questioned about health-related behavior. Data were analyzed via Pearson’s Chi-squared test. Results: Almost 70% of the participating patient population (n = 90) incorrectly perceived their weight category, with 62% underestimating their weight. Only 34% of patients who were overweight and 14% of patients with obesity correctly identified their weight status. Two-thirds of patients who were overweight and one-fifth of patients with obesity considered themselves to be “normal” or “underweight.” Patients with obesity were 6.5-fold more likely to misperceive their weight status. Amongst patients with overweight/obesity, those who misperceived their weight were significantly less likely to have plans to lose weight. Almost 60% had not made any recent health behavior changes. This is one of the first regional Australian studies demonstrating that hospitalized patients significantly misperceive their weight. Conclusion: Patients with overweight/obesity had significantly higher rates of weight misperception and the majority had no intention to lose weight or to undertake any health behavior modification. Given the association between weight perception and weight reduction behavior, it introduces barriers to addressing weight loss and reducing the increasing prevalence of obesity in rural Australia. It highlights that doctors have an important role in addressing weight misperception.