Résumé : Objective: To validate the technique of HIV-1 culture from whole blood for the quantitation of viral load in infected children. Patients: Forty-three HIV-1-infected children were followed in two paediatric centres. Methods: Quantitative HIV-1 cultures from unfractionated whole blood using an end-point dilution technique were compared with simultaneous quantitative cultures of peripheral blood mononuclear cells (PBMC) and plasma. Results: Good sensitivity (93%) of the methods used was confirmed. A close correlation (r = 0.80) was observed between HIV-1 titres measured directly from whole blood and those expected from PBMC and plasma titres. The mean whole blood viral load was higher in patients with more severe signs of disease, but the difference did not reach statistical significance. The whole blood viral titres measured sequentially at monthly intervals remained within one dilution of each other in 16 of the 22 patients studied. Conclusion: In this study, the quantitation of HIV-1 in unfractionated blood allowed for a reliable and sensitive measurement of the whole blood viral load in infected children.