Voriconazole (VRCZ) has a curious visual adverse event that is completely reversible, but its mechanism has not been fully addressed. We observed 20 consecutive patients treated with VRCZ after chemotherapy for hematological malignancy. Six of these cases experienced visual disturbance, and all cases among those treated with oral VRCZ. The authors discuss a relatively higher frequency of visual events complicated with hallucination, which might be associated with a special metabolism of VRCZ in Japanese patients with hematological malignancies. Hallucination and oral administration were specific clinical features for the patients presenting with visual adverse events in response to VRCZ.