Colonic leiomyomatous lesions are smooth muscle tumors including both benign leiomyoma and malignant leiomyosarcoma. They usually occur in elderly and middle-aged groups. They are rare, representing 3% of all gastrointestinal leiomyomas. Descending and sigmoid colon are the most commonly affected segments of colon. Patients are usually asymptomatic but occasionally they may present with abdominal pain, hemorrhage, and intestinal obstruction. Radiological findings for these lesions are variable and overlapping with other diagnoses but usually manifest as large lesions with lobulated margins, extra-colic growth, and heterogeneous enhancement. Final diagnosis is achieved by tissue diagnosis in which immunohistochemistry is used to differentiate them from other types of mesenchymal tumors like gastrointestinal stromal tumor. A complete surgical/endoscopic resection is usually curative with an excellent prognosis in cases of benign leiomyoma. In cases of leiomyosarcoma, post-surgical chemotherapy and radiotherapy are usually needed with a five-year survival of about 50%. We report the radiological findings with pathological correlation and literature review of two cases of colonic leiomyomatous lesions that presented with nonspecific abdominal pain. The lesions were resected surgically and confirmed histopathologically as leiomyoma and leiomyosarcoma of the colon, respectively. To the best of our knowledge, these cases are the first of colonic leiomyomatous lesions to be reported in Oman.