Objective To study the effect of bone marrow collected from 30 patients with cerebral palsy amount on proliferation of bone marrow mesenchymal stem cells (human mesenchymal stem cells, hMSCs) isolated in vitro. Methods Wall attached hMSCs in bone marrow of patients with cerebral palsy were isolated by centrifugalization, cultured in vitro, the adherent cells were passaged and reserved. The patiants were divided, according to age, into infant group (1-3 years, n=14) and children group (3-12 years old, n=16); and were grouped, according to the amount of bone marrow harvested, infant group (10-20 ml, 6 cases) and more than 20 ml (20-33 ml, 8 cases). The relationship botween bone marrow cell amount harvested and passage time in the two groups of cerebral palsy pationts was observed. Results (1) In infant group and children group of patients with cerebral palsy, between the bone marrow amount and P0, P1, P2, P3, P4 generation cell passage time, there were no significant differences. (2) In the infant groups and children groups, there was no difference between passage time less than 20 ml group P3, where as P4 passage time performance in the infant group was significantly faster than that in the children group (t=3.15, P<0.02). (3) In infants and children greater than 20 ml groups, P0, P1, P2, P3 passage time had no significant difference (P>0.05), where as P4 passage time in the infant group was significantly faster than that in children group (t=2.23, P<0.05). Conclusions In patients with cerebral palsy, hMSCs in vitro proliferation rate is not increased with increasing amount of bone marrow harvested.