Gastrointestinal nematode parasitism is a global problem in both sub-tropical and tropical countries. Due to frequent administration of chemical anthelmintics the gastrointestinal nematodes have developed resistance hence giving rise to the search of alternative anthelmintics. This study was carried out to evaluate anthelmintic effects of Tithonia diversifolia in Mbinga district, Ruvuma region, Tanzania. The study specifically dealt with evaluation of the efficacy of T. diversifolia extracts against adult Haemonchus contortus worms in a controlled critical test. Further, the toxicity of the plant was evaluated using the brine shrimp lethality test. A total of fifteen goats which were free from helminthosis were purchased and quarantined for 60 days. They were then administered 1250 larvae of Haemonchus contortus. On day 29 after infection the egg per gram of faeces (epg) count was done. The goats were randomly divided into three groups of five goats each .The groups were negative control, treated and positive control. The treatment group was administered 50 mg/kg of T. diversifolia orally and the positive control group was administered 8mg/kg of albendazole orally. The epg count was then carried out on day 4, 7, 10 and 14, after which animals were sacrificed for total worm count. The results show that Tithonia diversifolia is not effective against adult Haemonchus contortus worms based on epg count and post-mortem worm counts reduction tests. From the study, it is recommended that more studies should be carried out so as to validate the anthelmintic effects of T. diversifolia by investigating its activity on other specific species of the nematodes which parasitize animals.Belgium Technical Cooperation (BTC)