As reported in Egypt, the grasshopper Euprepocnemis plorans plorans is considered as a serious pest to crops in some regions. The objective of the current investigation was to evaluate the toxic and disruptive effects of the anti-JH compound, Precocene II (PII), on this pest. Nymphs of the newly moulted 2^nd and 4^th (penultimate) instars had been exposed to the doses: 60, 40, 20 and 10 µg/cm².  Complete mortality of nymphs was observed within 24 h of exposure of 2^nd instar nymphs to the higher two doses. At other doses, PII exhibited a remarkably extended low toxicity on the subsequently moulted nymphal instars and emerged adults. After exposure of the 4^th instar nymphs to PII, no complete mortality was observed, but various mortalities had been recorded among the treated nymphs, 5^th instar nymphs and adults. LD₅₀ values of PII were calculated as 0.388 and 17.022µg/cm², after treatment of 2^nd and 4^th instar nymphs, respectively. After treatment of 2^nd instar nymphs with PII, the nymphal growth of both 4^th and 5^th instars was insignificantly inhibited, regardless the dose. Exposure of 2^nd instar nymphs to the lowest dose of PII led to 3.33% precociously moulted nymphs into 4^th instar, skipping off the 3^rd instar. On the other hand, exposure of 4^th instar nymphs to the higher tow doses of PII induced some treated nymphs to precociously metamorphose into adultoids, skipping over the 5^th instar. Some permanent nymphs (3.85%) appeared among the 2^nd instar nymphs after exposure only to 20µg/cm². Also, similar permanent nymphs were induced during the 4^th instar. No permanent nymphs had been induced after exposure of 4^th instar nymphs to PII.