Abstract:Construction accidents don't just happen, they are initiated by unsafe acts, unsafe conditions or both. The construction industry in Kenya plays a vital role in achieving social and economic development goals, providing shelter, infrastructure, and employment. A study was carried out to identify the common accidents in construction sites and to examine the characteristics of the injured and deceased workers and evaluate factors that cause these accidents in Nairobi County, Kenya. The study cross examined data from Directorate of Occupational Safety and Health (DOSH) from Nairobi County ranging from 2010-2014. The study also utilized on-site questionnaires that were administered to 60 contractors in 9 administrative regions in Nairobi County. They constituted all class NCA2 contractors in the county as well as a few NCA3 and NCA4 contractors. Some 41 questionnaires were returned. Accidents were classified by the age of workers, time and month of the accident, location of an accident, causes of accident and management factors affecting the accident. The study established that 65% of all reported accidents occurred to workers below 37 years old. The accidents peaked between tea break (10am), lunch break (1pm) and after lunch (3pm) and during the months of June and July. The study determined that most construction site injuries were as a result of workers falling from heights (37%), being hit by falling objects (28%) and accidents occurring as a result of workers operating equipment (20%). Relative Importance (R. I) index of construction hazards were calculated for 24 factors contributing to construction site accidents. The top five hazards identified were: (1) reluctance to provide resources for safety (0.820); (2) lack of staff training (0.814); (3) lack of a safety policy and enforcement of safety regulations (0.795); (4) poor safety consciousness among workers (0.766); and (5) lack of strict operational procedures (0.756) in construction sites. The study concluded that in order to improve safety in the construction industry, each company should have a health and safety policy which is to be implemented in each contract. Furthermore, construction companies need to provide workers with the necessary Personal Protective Equipment (PPE), such as safety belts, retaining belts, safety ropes, and safety harness, and catch nets to prevent workers from being hit by falling materials and to secure them against falling from heights.