Thirty-five RA patients with the disease history from 3 months to 15 years were examined. Seropositive RA was diagnosed in 19 patients, seronegative in 16 ones. A control group comprised 14 subjects aged 18-29. The marrow cells culturing occurred in the system agar drop-liquid. Compared to the reference group, in RA patients' precursor cells of granulomonocytopoiesis there was inhibited capacity for colony and cluster formation and predominance of small-size cell colonies. Colony-formation of marrow cells from seropositive RA patients was less active than in seronegative RA variant. Morphologic evaluation of the agar cultures showed prevalence of neutrophil colonies in the marrow cultures, though RA samples differed from those of healthy controls by a trend to a decline in the number of monocyte-macrophage cellular aggregates against similar proportions of eosinophilic colonies and clusters.