The olive leaf moth Palpita unionalis (Lepidoptera: Pyralidae) is an economic pest of the commercial olive groves in Egypt and different Mediterranean countries. The present study was conducted aiming to assess the effects of Novaluron, a chitin synthesis inhibitor, on survival, growth, development and metamorphosis of this pest. The newly moulted last instar (6th) larvae had been treated with six concentrations (100.0, 10.0, 1.00, 0.10, 0.01 and 0.001 ppm), via the fresh olive leaves, as food. Different degrees of toxicity were recorded on all developmental stages. LC 50 was calculated in 0.97 ppm. The somatic weight gain of larvae was drastically reduced and the larval growth rate was severely regressed, regardless the concentration. The larval duration was generally shortened but the pupal duration was remarkably prolonged, in a dosedependent manner. The pupation rate was regressed, especially at the higher four concentrations. The metamorphosis program was impaired, since larvalpupal intermediates had been produced at some concentrations. In addition, the pupal morphogenesis was disrupted, since some pupal deformities had been observed at some concentrations.