Background:The lack of posterior abutments is the major problem in Kennedy class I removable prosthesis because of lack of partial denture retention and stability .Short implants can be used in case of alveolar bone heights less than 10mm, the focused question is In partially edentulous patients presenting severe resorption of the posterior region of the jaws, can topical application of melatonin improve short implant success rate? Methodology: Eight partially edentulous patients with mandibular posterior bilaterally free end saddle (Kennedy class I) were recruited to participate in this study, The study was a split-mouth study. Each patient served as his own control (served into 2 groups), the study side (topical application of melatonin in the molar area implant side), and the control side (no melatonin in the other implant side of the same patients at the molar area). Direct digital periapical sensors were used for assessing bone volumetric changes (bone height and bone density), this record were done 3 months, 6 months and 1 year from the baseline.  Result: result revealed that there was insignificant difference between Group I & II regarding bone density & height in all follow up periods as (P-value > 0.05) Conclusion: According this clinical study, Melatonin effect on increasing bone implant contact and bone density and bone height is unclear. further clinical study on human is necessary to know the effect of melatonin on the bone volumetric changes