The efficacy of three plant extracts - garlic, oregano and turmeric - in inhibiting larval development of Ascaridia galli eggs was evaluated in vitro. About 2000-2500 A. galli eggs were incubated per treatment and replicated five times. Ethanolic extracts of plant materials were diluted in phosphate buffered saline to form a dose concentration of 50 mg/ml. After 21 days of incubation under room temperature, results revealed that the three plants were as effective as albendazole in inhibiting the development of A. galli eggs on the 10th day of incubation. Garlic and turmeric were found to be effective but were no longer as efficient as albendazole on day 14 and day 21. Among the three plants, garlic was the most effective in inhibiting the development of the eggs since it did not go beyond the morula stage until day 21. On the other hand, the number of eggs that formed into larval stage was lower in turmeric than in oregano. This study indicated that garlic, oregano and turmeric can be used to prevent A. galli eggs development into L3 stage and hence, may prevent roundworm infection in chicken. However, supplementation must be programmed in order to retain their efficacy.