An experimental 2.15% imidacloprid gel bait containing ≈44% water was evaluated in laboratory and field studies against the German cockroach, Blattella germanica (L.). In continuous exposure tests, toxicity and presumably bait consumption varied with cockroach stage, deprivation of competitive food, and temperature. The LT₅₀ values for cockroaches provided with competitive food ranged from ≈0.9 h for adult females to 190 h for small nymphs. The LT₅₀s for cockroaches not provided competitive food ranged from ≈1.7 h for adult females to ≈31 h for adult males. The LT₅₀s decreased exponentially with temperature between 10 and 30°C. Even though the bait was significantly more repellent (≈38%) than an untreated control (≈14%) when tested in Ebeling choice boxes, performance index values were positive and increased to nearly 100 (indicating high mortality and low repellency) after 14 d. When applied at 15–45 g per kitchen, the bait significantly reduced German cockroach trap catch in infested homes during a 4-wk period. There was a ≈50% reduction after 1 wk and ≈80% reduction 4 wk after treatment.