BACKGROUND: Abomasal ulcer is a disease of digestive system in ruminants. The clinical signs vary widely depending on the type of abomasal ulcer. The economic losses of this disease include decreased milk yield and mortality. OBJECTIVES: The present study aimed to determine the frequency, type of ulcer, pathological, hematological, and electrocardiographic indices in the slaughtered cattle in Sanandaj abattoir. METHODS: A total of 400 cattle were randomly selected with both sexes and 1-2, 2-3, 3-4, and ≥4 years of age. They were grouped during three seasons and the abomasal ulcer was evaluated. Blood sample was collected and electrocardiogram was recorded before they were slaughtered. Abomasal lesions were assessed macroscopically and histopathologically in the slaughtered cattle. RESULTS: Out of the 400 abomasom examined, 51 (12.75 %) were affected by abomasal ulcers, all of which were type-1 ulcer. Subtypes 1a, 1b, 1c, and 1d. 35 cattle (68.7 %) had the types of arrhythmia. The most frequent of them was sinus arrhythmia and sinus tachycardia. Neutrophilia and reduction in MCHC were significantly more than the other hematological indices (p < /em>˂0.05). There was a significant relationship between the prevalence of abomasal ulcers and arrhythmia, gender, age, and season (p < /em>˂0.05). Furthermore, there was a significant relationship between electrocardiographic and hematological indices in the affected cattle (p < /em>˂0.05). CONCLUSIONS: The results of this study revealed a high prevalence of abomasal ulcer in the studied area. They also indicated that the electrocardiographic and hematological changes could be helpful in the diagnosis of abomasal ulcer.