Background: Mechanical intestinal obstruction is a common and potentially dangerous surgical emergency with high morbidity and mortality worldwide. An estimated 20% of hospital general surgical emergency admissions are for the management of intestinal obstruction. Early diagnosis and timely definitive surgical procedure is of paramount in order to improve the chances of survival of patients with this condition. Moreover, the management of mechanical intestinal obstruction poses therapeutic challenges to general surgeons practicing in resource-limited countries including Tanzania. Aim: To determine the aetiologies and managements of mechanical intestinal obstruction among patients admitted and treated in surgical department at KCMC from January to December 2015. Methodology: This was descriptive cross sectional hospital based study, secondary data from the medical records were used. All patients diagnosed and treated for mechanical intestinal obstruction at KCMC surgical department from January to December 2015 and met the inclusion criteria were included in the study. Data was collected using data collection form, processed and analyzed by using Statistical Package for Social Science (SPSS) version 20. Data was summarized in form of proportions and frequency for categorical variables and range and median for continuous variables. Tables and figure were used to present results. Results: A total of 120 patients with age ranging from 1-97years and median age of 47years with male to female ratio of 1.9:1, were diagnosed and treated for mechanical intestinal obstruction. Adhesion was the commonest cause of mechanical intestinal obstruction contributing 46(38.3%) cases, followed by impacted stool 26(21.7%) cases. 89(74.2%) cases were managed surgically where by exploratory laparotomy was the most performed procedure in 80(89.9%) of the surgically managed patients and laparoscopic adhesiolysis in 9(11.1%)cases. 31(25.8%) were given conservative management. Conclusion: Adhesion and impacted stool are the leading causes of mechanical intestinal obstruction in our Centre, KCMC. Although some came be treated conservatively, a substantial portion requires immediate surgical intervention. Keywords: Mechanical intestinal obstruction, aetiology, management, KCMC, Tanzania.