The composition of essential oils from leaves of Kazakhstan medicinal plants was analysed by GC-MS. The major compounds identified were 1,8-cineole (34.2%), myrcene (19.1%) and α-pinene (9.4%) in Ajania fruticulosa; 1,8-cineole (21.0%), β-thujone (11.0%), camphor (8.5%), borneol (7.3%) and α-thujone (6.5%), in Achillea nobilis; camphor (47.3%), 1,8-cineole (23.9%), camphene (9.8%) and β-thujone (6.0%) in Artemisia terrae-albae; 1,8-cineole(55.8%) and β-pinene (6.2%) in Hyssopus ambiguus; α-thuyene(46.3%) and δ-cadinene(6.3%) in Juniperus sibirica; sabinene (64%) in Juniperus sabina; and α-pinene (51.5%), β-phellandrene (11.2%) and δ-cadinene (6.3%) in Pinus sibirica. The essential oils did not show antifungal effect (MIC>> 1.20 mg/mL) on Aspergillus carbonarius and Aspergillus niger, while the oils from A. nobilis, A. terrae-albae, H. ambiguus and J. sabina exhibited moderate and moderate to weak antimicrobial activities on Fusarium verticillioides (MIC = 0.60 mg/mL) and Fusarium graminearum (MIC = 0.60-1.20 mg/mL), respectively. A principal component analysis associated the antifungal activity (r2>> 0.80, p = 0.05) with the presence of borneol, camphor, camphene, 1,8-cineole,α- and β-thujone, and of the oxygenated monoterpenes.