The conclusion of the Locarno Accords in 1925 that defused to some extent the tense situation in Europe contributed to the appearance of other draft regional pacts — the Balkan, Baltic and East Locarnos. One of these draft treaties covered the Mediterranean region where there was no effective security system after WWI. The article discusses Barthou’s diplomatic measures for concluding a Mediterranean agreement. This idea dates back to the turn of the 1920s. Since this subject has not been adequately dealt with in the literature, the author, on the basis of various sources including little-known material from the archive of the French diplomat R. Massigli, analyzes the attitude of the French foreign minister to the agreement, specific measures that were taken for its implementation, and its significance among other French regional initiatives. The agreement covering the Mediterranean countries was to become one of the elements of the security system that the French minister was working on, although it did not play a primary role in his foreign policy since the French diplomacy regarded as the main threat Germany. Being the foreign minister, Barthou repeatedly evoked the idea of the pact, while modifying the list of its members due to the international situation. The simultaneous participation of Italy and Yugoslavia was fundamental. Their support was necessary in building the French minister’s security system. Nevertheless, he himself did not intend to initiate the conclusion of such an agreement, attempting to present it as a regional project. In the case of implementing the Mediterranean pact, Barthou thought to achieve rapprochement with Italy and to strengthen the influence of France in the Balkan region. However, this agreement did not meet the interests of other Mediterranean countries, and therefore, the French Minister’s attempts to include the draft pact in the international agenda were unsuccessful.