Pseudocysts of the adrenal gland are rare lesions, which are usually discovered as incidental findings. Since they are in the majority of cases non-functioning, they become symptomatic only when they are complicated with rupture, haemorrhage or infection. We present a case of a 28-year-old woman in the 26th gestational week, who developed an acute abdomen due to a haemorrhagic pseudocyst of the left adrenal. The patient was submitted to left adrenalectomy. The described case is the third reported case of cystic adrenal lesion discovered during pregnancy and only the first reported case of acute presentation of an adrenal pseudocyst during pregnancy.