In this work, we investigated the effects of scopolamine bromide, present in the formulation of several antiespoasmodic and analgesic medicines, on the development of Chrysomya megacephala. In addition to the control group, larvae of this fly were reared using and artificial diet containing the following concentrations of scopolamine bromide: the mean lethal dose (X) (1270 mg of scopolamine bromide/kg of diet, corresponding to the oral mean lethal dose for rats), half the mean lethal dose (X/2), 1/4 the mean lethal dose (X/4), and two times the lethal dose (2X). The effects on larval development were determined by comparing the results with the control group, reared with no drug. For each treatment group, 400 larvae were used. Weights and lengths were individually recorded for groups of 10 larvae at 6 hours intervals up to the end of the larval stage. The larvae reared in the mean lethal dose showed a significant reduction in the developmental time when compared to the control group. All larvae reared at concentration 2X died within 24 hours after hatching. Larvae reared at concentration X/2 had the development significantly delayed, and those reared in the concentration X/4 showed no significant difference with the control group. The results evidence that, depending on theconcentration, the presence of this drug significantly affects the larval development, and can lead to errors in the estimate of the postmortem interval.