Ash weevil is the most common and most important defolijator of ash in the countries of Southeast Europe. The paper presents the results of research of the morphological characteristics of ash weevil. Dimensions of ash weevil developmental stages were determined by measuring on a larger number of specimens. Morphological characteristics were described and documented in photographs and drawings. Sexual dimorphism of the ash weevil is poorly expressed, and males and females can be distinguished by the structure of the last abdominal segment. Body length of males is from 2.95 mm to 3.48 mm, and females from 3.11 mm to 3.80 mm. Ash weevil eggs are white - yellow length of 0.52 mm to 0.70 mm, a width of 0.33 mm to 0.42 mm. The larvae have three stages of development. Larvae of first instar have a width of head capsule from 0.16 to 0.23 mm. In the second instar width of 0.34 to 0.50 mm, and in the third instar larvae head capsule width from 0.54 to 0.66 mm. Pre-pupa body is a length of 3.10 to 3.95 mm. Pupa length is from 3.11 mm to 3.89 mm.