Hydrops fetalis is a Greek term for the pathological accumulation of fluid in the soft tissues and cavities of the foetal body. The diagnosis is made on the basis of an ultrasound examination confirming the accumulation of fluid in at least 2 foetal compartments. The paper presents the comparison of 2 clinical forms stemming from non-immune hydrops fetalis (NIHF). The following description highlights diagnostic difficulties related to the fact that the cause of the above conditions may not always be possible to determine. The continuation of multidirectional action, including both diagnostic work-up and treatment, is fundamental to the success of the treatment process, regardless of the location of the accumulated fluid and the unknown cause. The clini­cal condition is of key importance to the management of the newborn.