Dolycoris penicillatus Horwàth has been reported as one of the harmful bugs to cereal crop in Iran as well as some countries in the region. Overwintered adults occasionally appear in massive populations in the early spring in some parts of the country including highlands of the mountain range of Binalood, Khorasan province. In order to study its demographic parameters, one hundred eggs were taken from a colony originated from Mashhad, Khorasan province, and were individually put in transparent plastic containers under climatic conditions (temperature 25 ± 1 ° C, relative humidity 50% -60%, and a photoperiod of 16: 8 L: D h.). From emerging the second instar nymphs onwards the insects were provided with soaked wheat grain and green wheat foliages until the end of new adults’ lives. During this period, every individual was recorded on a daily basis for all biological events (hatching eggs, moulting, oviposition and mortality). The Age-Stage, Two-Sex life table software was used to analyze the data. The estimated demographic parameters were: intrinsic rate of increase (r = 0.064 ± 0.004 per day), finite rate of increase (λ = 1.066 ± 0.004 per day), net reproduction rate (Ro = 54.83 ± 13.23 offspring / individual), gross reproductive rate (GRR = 134.38 ± 31.77 offspring / individual) and the mean generation time (T = 62.46 ± 1.51 day). Regarding the demographic parameters reported for the most serious sunn pest, Eurygaster integrethis, it can be concluded that reproduction potential of the both species are similar under laboratory conditions.