The Moldavian dragonhead Dracocephalum moldavica L., of the Lamiaceae family, is a grassy annual plant up to 80 cm tall. The herbaceous part contains an essential oil, flavonoids, iridoids, tannins, and hydroxycinnamic and carboxylic acids. The quantitative composition of the iridoid glycosides was studied using aqueous and alcoholic extraction of Moldavian dragonhead herb. Chromatography was performed on “Sorbfil” plates using a variety of solvent systems. Compounds were identified in terms of the luminescence-chromatographic characteristics of spots on chromatograms and Rf values. Extracts were found to contain from four to six iridoid compounds, of which spots with Rf values of 0.43 and 0.89 were identified as harpagide and harpagide acetate respectively. The quantitative contents of iridoid glycosides were evaluated by spectrophotometry based on estimation of the products of the hydroxamic reaction. Harpagide acetate was selected as the standard substance. The relative estimation error with confidence limits of 95% was ± 2.8%. The investigations reported here showed that the optimum conditions for estimating iridoid contents were as follows: particle size no greater than 1 mm with extraction of starting material with 70% ethanol at a ratio of 1:40 for 1 h in a boiling water bath. Iridoid contents were determined in Moldavian dragonhead herb prepared at the budding stage (0.11–0.27%), at mass flowering (0.18–0.51%), and at fruiting (0.04–0.30%); the greatest iridoid content (0.51%) in the herbaceous parts of the Dracocephalum moldavica was seen at the mass flowering phase.