BACKGROUND Neutropenia recovery (NR) has been associated with worsening preexisting lung injury in up to 50% of critically ill cancer patients. However, only limited relevant data exist in the general population of hematological patients. OBJECTIVES To assess the incidence of acute respiratory deterioration during NR in patients with hematological malignancies. METHODS Adult patients with neutropenia expected to last more than 7 days were included. Worsening of respiratory status (WRS) was defined as a decrease in oxygen saturation of ≥5%, the need for oxygen therapy for ≥24 h, an increase in oxygen flow of ≥50% in patients previously treated with oxygen, or the need for mechanical ventilation. NR was defined as the 3 days preceding or following a neutrophil count of >0.5 × 109/l. RESULTS A total of 16 of 50 patients included in this pilot study experienced WRS during NR (32%), and 13 patients had WRS during neutropenia (26%). The incidence density of WRS was 0.53 (±0.79) episodes per 10 days during NR and 0.20 (±0.39) episodes per 10 days during neutropenia (p = 0.004). Sepsis, stem cell transplantation, preexisting pneumonia, or the use of granulocyte colony-stimulating factor were not associated with WRS during NR. CONCLUSION Up to one third of noncritically ill hematological patients with expected neutropenia of more than 7 days experience WRS during NR. Clinical consequences and risk factors for WRS during NR remain to be evaluated.