Predicting poor stem cell mobilization may prevent the costs and complications associated with remobilization. We retrospectively reviewed the relationship between serum lactate dehydrogenase (sLDH) activity and peripheral blood CD34 (PBCD34) cell counts in 46 granulocyte colony stimulating factor (G-CSF) induced mobilization cycles with or without chemotherapy. A significant correlation between post-mobilization (pre-apheresis) sLDH activity and PBCD34 count was found (r(s) = 0.43, p = 0.007). A strong correlation was shown between the pre- and post-mobilization sLDH activity difference and PBCD34 count (r(s) = 0.55, p = 0.001). With respect to sLDH activity differences; (a) all patients with a difference of >300 U/L, (b) 71% of patients with a difference of 100-300 U/L, and (c) 44% of patients with a difference of <100 U/L were considered to have good mobilizations. The sLDH activity difference between pre- and post-mobilization is a good indicator of successful mobilization. According to our results, the success of mobilization can be predicted based on sLDH activity differences; (i) good mobilization if the difference is >300 U/L, (ii) intermediate risk if the difference is 100-300 U/L, and (iii) high risk if the difference is <100 U/L. (C) 2012 Elsevier Ltd. All rights reserved.