Beside the main issue of the Lekarz Wojskowy (LW) magazine, there was also its secret edition, published in the period of 1964–1989, intended to train the military medical personnel in case of war. In total, 40 issues of the secret version of LW were published, including 504 papers written by experts in various areas of both military and clinical medicine. The aim of this article is as follows: (1) an analysis of the subject of those papers according to particular disciplines of military medicine; (2) a comparison of their content structure in three political and social periods: 1965–1969, 1970–1979 and 1980–1989, and (3) a presentation of detailed issues raised in the LW secret edition. The results. (1) Most papers concerned the Armed Forces’ Healthcare Organization (OOZW) – 27.5%, hygiene and epidemiology – 19.2%, field surgery and general medicine – 17.9% in total, and social medicine – 15.5%. (2) Over the years, the share of papers referring to the OOZW remained large, while those on military hygiene and epidemiology were on the decline, and in the same time the share of field surgery, general medicine and social medicine papers was growing. (3) Publications presented in the LW secret issues are a valuable source of information on the history of Polish military healthcare system. These publications are important enough to be digitalized in order to be integrated into the scientific data circulation and prevented from destruction.