Peripheral blood progenitor cells are being used increasingly as part of the treatment protocol for a variety of haematological malignancies. The most appropriate mobilisation therapy and the optimum collection procedures have yet to be fully elucidated. 28 patients with myeloma (9), NHL (11) and HD (8) underwent PBSC mobilisation and harvesting between November 1992 and October 1993. Two protocols were used; the myeloma group received high-dose cyclophosphamide, 7 g/m2 + G-CSF and were leucapheresed on 5 consecutive days during the recovery period using the Haemonetics V50 and the lymphoma group a lower dose of cyclophosphamide, 3 g/m2 + G-CSF followed by leucapheresis on 2 or 3 occasions using a Cobe Spectra. Median time to achieve a WBC of 1 x 10(9)/l during the recovery phase, was 14 days (11-16) and 10 days (9-15) respectively. Median numbers of MNC and CFU-GM collected for the myeloma group were 5.9 x 10(8)/kg (2.5-13.5) and 69.4 x 10(4)/kg (9.9-268.1) and for the lymphoma group. 5.1 x 10(8)/kg (1.2-11.1) and 35.4 x 10(4)/kg (1.2-129.7). Three patients with lymphoma had a low yield of CFU-GM, two of which did not proceed to autograft. The third patient failed to engraft and died despite receiving bone marrow backup. For the remaining 25 patients, median time to neuts > 0.5 x 10(9)/l and platelets > 50 x 10(9)/l was 9 (8-13) and 11 (9-23) days for the myeloma group and 12 (9-15) and 13 (9-180) days for the lymphomas. We found a strong correlation between CD34+ cells and CFU-GM from the last 9 patients. There is a correlation between CFU-GM infused and speed of engraftment. All patients who received > 10 x 10(4) CFU-GM/kg showed a rapid engraftment for neutrophils and platelets. In all cases, when > 4 x 10(8)/kg MNC were harvested, > 10 x 10(4) CFU-GM/kg were obtained. Sufficient cells for a rapid engraftment can be obtained from 2 leucaphereses in the majority of patients. The recovering peripheral blood WBC provides a good indicator of when to harvest. The target value of CFU-GM can be predicted by the number of cells harvested and by the number of CD34 positive cells in the leucapheresis product.