The progenetic metacercariae of Clinostomum complanatum have been used as an excellent experimental model in various laboratory studies to elucidate the biology, life cycle, ultrastructure and for the determination of the efficacy of different specific enzyme inhibitors and some natural products (Abidi and Nizami, 2000; Dias et al., 2003; Rizvi et al., 2012; Shareef & Abidi, 2012; Rehman et al., 2017). The incidence of these larval stages is considerably high in the forage fish Trichogaster fasciatus in the Aligarh region (Khan et al., 2013), and the zoonotic potential of these worms is also significant, as evident from reports on human infections, which have been reported to cause severe laryngitis and pharyngitis (Chung et al., 1995; Park et al., 2009; Hara et al., 2014; Song et al., 2018; Kim et al., 2019). Most of the anthelmintic drugs that are currently used are effective against the adult forms but not against the larval stages, except for triclabendazole (TCBZ), which is equally effective against both adult and juvenile flukes; however, resistance is emerging in trematode flukes against TCBZ worldwide (Kelley et al., 2016; Fairweather et al., 2020). Given the emerging anthelmintic resistance to commonly available drugs, there is an urgent need to explore alternative therapeutic molecules. Curcumin, an active ingredient of the relatively inexpensive Indian spice Curcuma longa, has been reported to have diverse therapeutic potentials (Johnson and Mukhtar, 2007; Mishra et al., 2009; Magalhães et al., 2009; Nayak et al., 2012, 2012 de Paula et al., 2016; Ullah et al., 2017; Rehman et al., 2020). The effects of curcumin on adult worms have already been established (Nayak et al., 2012; Ullah et al., 2017; Rehman et al., 2020). However, very limited information is available regarding the effects of curcumin on larval forms (Matos et al., 2020). Understanding the zoonotic potential of C. complanatum and also the anthelmintic properties of curcumin motivated us to investigate its effect on the progenetic metacercariae of C. complanatum that harbours immature eggs and thus possess the characteristics of both the larval and adult parasite (Shareef & Abidi, 2012). Therefore, in the present study, we have aimed to establish the in vitro efficacy of curcumin against larval worms.