Manihot esculenta leaf meal in feed at post-hatch improves growth and egg production. One may question the efficacy of Manihot esculenta leaf extract for in ovo feeding. This study was conducted to determine the effects of in ovo injection of Manihot esculenta extract on hatchability, growth performance and biochemical parameters of Sasso broiler chickens. The hatching eggs from 38-week-old broiler breeders were set and at d 18 of incubation, 600 eggs with evidence of living embryos were assigned to 4 treatment groups of 150 eggs each. These groups were: (1) eggs without in ovo injection (negative control); (2) eggs perforated but no injection of any additive (positive control); (3) eggs perforated and injected with 0.1 ml of saline solution and (4) eggs perforated and injected with 0.1 ml of Manihot esculenta extract. Data were collected on hatching performance. During the post hatch growth phase, performance traits such as feed intake, weight gain, and feed conversion ratio were collected and at 84 days of age, blood samples were taken for determination of serum total proteins, triglycerides, aspartate aminotransferase (ASAT) and alanine amino transaminase (ALAT). The results showed that hatchability was similar in the negative control and Manihot esculenta extract groups but significantly higher (P < 0.05) than those of positive control and saline solution treatment groups. Chick quality was better in the groups with Manihot esculenta extract and saline solution application. Post-hatch, the body weight gain of birds from the Manihot esculenta extract group was higher than those in the groups with saline solution application and in the negative control and positive control groups.Manihot esculenta leaf extract increased significantly the triglyceride rate and reduced ALAT and ASAT concentration at hatch. It can be concluded that in ovo inoculation of 0.5 μg/ml Manihot esculenta leaf extract on d 18 of incubation into the eggs air chamber improved hatchability, chick quality and post-hatch growth of broilers.