In order to analyze the cai]ses of delayed diagnosis and raise the level of early diagnosis of atypical multiple myeloma (MM), the differences of presenting features between the patients presented to nephrologists and those presented to hematologists were compared. MM patients in our hospital were studied retrospectively. Those who referred renal impairment were divided into two groups: group I presented to nephrologists prior to MM diagnosis (n=29) and group II presented to hematologists directly (n=62). The age, sex, initial symptoms, haematological and biochemical parameters, the phenotype of paraprotein, bone marrow biopsy and cytology were undertaken and analyzed. The results showed that the median time between the initial symptoms and diagnosis in the patients of group I was longer than that in group II (P<0.001); patients in group I had significantly lower incidence of bone pain (P<0.01) and worse renal function (P<0.05) on presentation. There were lower level of myeloma cells (P<0.05), lower incidence of hypergammaglobulinemia (P<0.05), lower positive rate of monoclonal immunoglobulin (M protein) (P<0.05) and M protein level (P<0.05) in the patients of group I than those in group II. The ratio of monoclonal to lambda monoclonal proteins in a population was 1:3.67 in patients of group I, whereas 1:0.90 in patients of group II (P<0.01). Moreover, patients with λ type had a higher degree of renal insufficiency than those with κ type (P<0.05). It was suggested that the median time between the initial symptoms and diagnosis in the patients presented to nephrologists was longer than that in those presented to hematologists; the patients presented to nephrologists had the lower incidence of bone pain, lower level of myeloma cells and M protein, which made early diagnosis more difficult; more patients presented to nephrologists had the majority of λ light chain type, moreover, patients with λ light chain type had a higher incidence of renal insufficiency.