The small brown planthopper Laodelphax striatella (Fallén, 1826), which belongs to Delphacidae family, is widespread in Palearctic. It is one of the important pests of agricultural crops such as rice, maize, oat, wheat etc. Because of its economic importance, identification of the factors that effective on L. striatella populations is required. Size of body parts closely related with vital processes such as metabolic performance, fecundity, and longevity. Several ecological factors such as light, temperature, water supply and moisture were effective on body size. The aim of the study was to determine the effect of altitude on some body measurements of L. striatella. Because light, temperature, precipitation and some of the other factors vary based on altitude, it is an important ecological factor for organisms. Understanding the effects of altitude on insect species may give useful information about them. The specimens were collected from three localities at different altitudes in Central Black Sea Region, Turkey. Except wing length, all the measurements of the body parts varied proportionally with increasing altitude. Statistically significant variations were determined in the measurements of head width, pronotum length, pronotum width, mesonotum width and forewing width. The maximum head, pronotum, mesonotum and forewing width (0.623, 0.686,0.707 and 0.730 mm, respectively) and pronotum length (0.172 mm) was measured at 50 m. The minimum measurements of these body parts were at 900 m. Additionally, relationships were determined between measured body parts and altitude.