AIM To determine the prevalence of Monoclonal Gammopathy of Undetermined Significance (MGUS) in Nigerians. OBJECTIVES 1. 2 3. 4. To identify the presence of an M protein component in the serum of the general population in Nigeria To determine the type and concentration of the M protein. To determine an association if any between the presence of M protein and some haematological parameter such as ESR, Haemoglobin level, packed cell volume, lymphocyte count. To identify the predisposing factors if any to the development of MGUS - age, sex, history of chronic disease or infections. Study design This was a cross sectional study conducted on apparently healthy adult volunteers selected by a multistage sampling technique from the general population in Lagos. Lagos state is a cosmopolitan city located in the southwestern region of Nigeria. Materials and Method. Four hundred and fourteen (414) participants who satisfied the inclusion criteria were enrolled into the study. A 2-step screening was performed with a serum protein electrophoresis followed by Immunofixation and a quantitative determination of serum concentration of immunoglobulins when a monoclonal band was found. Haematological and biochemical parameters of the participants were also evaluated.