Chromosome analysis has become an important diagnostic tool in the assessment of patients with multiple myeloma. Conventional cytogenetic analysis of myeloma cells is complicated by the difficulty in inducing myeloma cells to divide. A method for the culture and harvest of bone marrow samples from patients with myeloma is presented together with a protocol for producing G-banded metaphases for microscopic analysis. It is recommended that two or more cultures be established from each sample. There is extensive literature describing the use of various cocktails of mitogens to assist in obtaining dividing myeloma cells with little consensus as to the optimal method. A protocol is given for stimulating cells to divide using interleukin-4, the method in routine use in the Victorian Cancer Cytogenetics Service.