Exposure to inorganic mercury (Hg) is a serious problem presenting with a combination of neurological and psychiatric symptoms along with weight loss, pruritus, erythema, arterial hypertension, tachycardia, and renal tubular dysfunction. We report a 4-year-old girl with chronic intoxication of inorganic mercury secondary to the accidental use of an Hg₂Cl₂- and HgCl₂-containing skin whitening cream (urine level of Hg, 41.1 μg/l; reference level, < 25 μg/l). Under treatment with dimercapto-1-propansulficacid, Hg level in the urine raised to 1,175.5 μg/l, neurological deterioration occurred, and brain magnetic resonance imaging (MRI) showed on fluid attenuated inversion recovery sequences new hyperintense lesions in the subcortical white matter. After 4 months, clinical signs and symptoms and brain MRI findings resolved. This is a first case of inorganic mercury poisoning showing hyperintense lesions in brain MRI and confirms earlier cases showing transient deterioration during chelation therapy. Although urinary excretion could be enhanced during chelation therapy, signs and symptoms of intoxication could be worsened.