Introduction: Anterior disc displacement is one of the major findings in Tempromandibular joint derangments TMDs, as well as the most common cause of Tempromandibular joint TMJ sounds uncoordinated function between the muscle bundles of the upper head and the superior part of the lower head of the lateral pterygoid muscle could lead to abnormal movements of the disc, therefore, causing a click. Aim: The aim of the present study was to investigate the effect of botulinum toxin type A injection in the lateral pterygoid muscle on temporomandibular joint clicking versus occlusal splint therapy. Patients & methods: The study enrolled forty patients divided into two equal groups. All patients were selected from the outpatient clinic, complaining of a painful TMJ click with muscle tenderness, associated with ADDR confirmed by magnetic resonance imaging. A BTX-A vial was diluted with normal saline to a concentration of 10 U per 0.1 mL for injection in a 1-ml insulin syringe. This was injected into the ipsilateral LP muscle with the guidance of an electromyogram device. Hard occlusal splint fabricated from transparent acrylic resin. Results: There was no statistically significant difference between pain, clicking and MMO in the two groups preoperatively. Group I showed the statistically significantly lowest mean pain scores. The mean MMO after 12 months showed statistically significantly higher mean value compared to pre-operative measurement in the two groups. Group I showed no clicking while Group II showed the highest prevalence of clicking. Conclusion: There was a significant increase in mouth opening from the start of treatment and till the end of the follow up period, concerning pain there is decrease in VAS values, and clicking improved postoperatively after 1 week in the first group while improved after first month in the second group, radiographic evaluation shows no change in MRI.