Abstract Natural mycelial biomass (MB) and exopolysaccharide (EPS) produced from bioreactor-grown Malaysian Tiger Milk Mushroom Lignosus rhinocerus are considered high-end components due to their high commercial potential value in drug discovery. Both MB (0.16-10 mg/mL) and EPS (0.16-10 mg/mL) extracts were tested for Zebrafish Embryo Toxicity (ZFET) and early development effects on Zebrafish Embryos (ZE) during 24-120 h post-fertilization (HPF) in order to assess toxicity given potential application as a new therapy for treating asthma. Finding revealed that MB was deemed to be safe with an LC50 of 0.77 mg/mL; EPS was shown to be non-toxic (LC50 of 0.41 mg/mL). Neither MB nor EPS delayed hatching nor teratogenic defects in treated ZE at a dose of 2.5 mg/mL. There were no significant changes in the ZE heart rate after MB or EPS treatments with MB (0.16-10 mg/mL: 130 beats/min) and EPS (0.16-10 mg/mL: 140 beats/min), as compared to normal ZE (120-180 beats/min). In addition, mixing of both natural compounds MB and EPS did not affect toxicity using ZFET testing; thus, intimating their safe future use as therapeutic interventions.