This study was conducted to investigate the effect of implant platform switching on strains developed around implants with straight and angled abutments.Samples of this study were divided into two groups:Group I: (n=10) ten straight implants with five straight abutments with matching diameter to that of the implant (4.5 mm) (sub-group A) and five straight abutments with platform switched smaller diameter (3.75) than that of the implant.(sub-group B).Group II: (n=10) ten inclined implants with five 15º angled abutments with matching diameter to that of the implant (4.5 mm) (sub-group A) and five 15º angled abutments with platform switched smaller diameter (3.75) than that of the implant.(sub-group B).All implants were inserted in epoxy resin blocks with the aid of a specially designed mould and paralleling device following a standardized protocol. The abutments were then screwed to the implants with the hex tool and torque wrench.All abutments received Ni-Cr full metal crowns representing upper premolar with non-anatomical occlusal surface following a standardized protocol.Crowns were cemented on their corresponding abutments using temporary eugenol-free cement. Epoxy resin models were prepared to receive four strain gauges around each implant. Then strain gauges were luted on the prepared epoxy blocks.After connecting the strain gauges to the strain meter, a 300 N load was applied axially on each crown using a universal testing machine at a rate of 1N/sec. The developed microstrains around each implant were recorded using a four channel strain meter.Results showed that platform-switching had a statistically significant effect on micro-strain developed around implants where implants with platform switched abutments were found to produce statistically significant lower micro-strain values than those with matching diameter abutments. Abutment angulation had a statistically significant effect on micro-strain developed around implants where implants with straight abutments were found to produce statistically significant less micro-strain values than those with angled abutments. Within the limitations of this in vitro study, the following conclusions could be drawn:1.Platform-switching and angulation of the abutments significantly affect micro-strains developed around implants.2.Platform-switched abutments reduces micro-strain developed around implants regardless of the abutment angulation.3.Straight implants with straight abutments are associated with lower micro-strain values than inclined implants with angled abutments with both abutment diameters.4.Straight implants with straight platform-switched abutments are associated with the least micro-strain values among all groups.5.Inclined implants with angled matching diameter abutments are associated with the highest micro-strain values among all groups.Recommendations:When using inclined implants with angled abutments, shift to platform-switching concept to decrease microstrains around the implants.