Pulmonary tumor embolism (PTE) and intravascular lymphoma cause rapidly progressive deterioration and an antemortem diagnosis is difficult. The usefulness of pulmonary microvascular cytology (PMC) in the diagnosis of these disorders has been reported in sporadic case reports. We retrospectively evaluated the records of 7 patients with tumor cells in the pulmonary microvasculature (4 with PTE and 3 with malignant lymphoma) who underwent pulmonary microvascular cytology. Two of the 4 patients with PTE and 2 of the 3 patients with malignant lymphoma (all 3 had intravascular metastasis) had positive PMC results. These findings suggested that PMC may be useful in the diagnosis of these disorders.