FIELD : medicine.SUBSTANCE : invention refers to immunology, and can be used for prediction of risk of formation of T-helper immunodeficiency in crew. Method for detecting a risk of forming a T-helper deficiency in sailors, involving counting the total number of leukocytes, lymphocytes and monocytes in blood. If observing lymphocyte concentration simultaneously, less than 1.5??109 kl/l and monocytes less than 0.35??109 kl/l a high level of risk of 90?% of T-helper immunodeficiency is predicted.EFFECT : use of the given method enables detecting individuals who are at risk of T-helper immunodeficiency in sea proficiency testing, as well as in order to prevent secondary ecologically dependent immunodeficiency in the shipboard personnel.1 cl, 6 ex