The rail sector, despite its potential for curtailing the present chaotic transport situation in Lagos, remains inefficient and underutilized. In spite of past initiatives and the current attempt by the Lagos State Government to provide a mass transit rail service in Lagos, the share of rail mode in the transport sector has not been encouraging and the railway plays an insignificant role in urban mass transit in Lagos at present. This paper sets out to assess the usage of the Lagos mass transit trains. Hence, the paper determines the passenger traffic flow along the rail route in Lagos and the number of passengers carried between 2000 and 2009 by the Lagos Mass Transit Trains (LMTT) with a view to assessing the usage of the present LMTT. This paper also discusses the historical development of Nigerian railway and describes rail transport in Lagos. Data were obtained through secondary sources coupled with review of literature. The result of this study shows that for a period of 10 years (2000-2009), Lagos mass transit trains carried a total of 9,870,101 passengers, which gives an average of 987,010 passengers annually. This suggests that the service of the Lagos mass transit train is grossly underutilized. However, LMTT contributes enormously to NRC by carrying 68.5% of the total passenger traffic of NRC between 2000 and 2009. In terms of passenger traffic flow along the route of LMTT, for a period of 1 year, Agbado station recorded the largest number of passengers (393,811), followed by Ijoko (163,652) and Iddo (120,787), while Iganmu station has the lowest number of rail commuters (16,919). This study also discloses that the major commodities hauled by Lagos district of NRC from Lagos to the northern parts of the country in 2007 are Cars, Cement, Billet and Wheat.