Purpose: To evaluate the efficacy of flapless versus open flap implant placement in partially edentulous patients. Materials and methods: Forty patients with two separate edentulous areas characterised by residual bone at least 5 mm thick and 10 mm in height had these sites randomised following a split-mouth design to receive at least one implant to each side after flap elevation or not. Implants were first placed in one site, and after 2 weeks in the other site freehand. Implants inserted with a torque >48 Ncm were immediately loaded with full occluding acrylic temporary restorations. Definitive single cemented crowns or screw-retained metal ceramic fixed dental prostheses were delivered after 2 months. Outcome measures were prosthesis and implant failures, complications, postoperative swelling and pain, consumption of analgesics, patient preference, surgical time, marginal bone level changes, and implant stability quotient (ISQ) values. Results: Seventy-six implants were placed flapless and 67 after flap elevation. In the flapless group, four flaps had to be raised to control the direction of the bur, whereas one haemorrhage and one fracture of the buccal bone occurred in two patients of the flap elevation group. Four implants did not reach the planned stability (three belonging to the flapless group) and they were all immediately replaced by larger diameter ones. After 1 year, no drop-outs occurred. Two definitive bridges could not be placed when planned (one in each group) and two crowns had to be remade (one in each group). Two implants failed in each group, all in different patients. There were no statistically significant differences for prosthetic and implant failures, complications, ISQ values and marginal bone levels between groups. However, flapless implant placement required significantly less operation time (17 minutes less, saving almost two-thirds of the time for implant placement), induced less postoperative pain, swelling, analgesic consumption and was preferred by patients. Mean ISQ values of both groups significantly decreased over time. Conclusions: Implants can be successfully placed flapless and loaded immediately, reducing treatment time and patient discomfort. Keywords: dental implants, flapless, immediate loading, partial edentulism, randomised controlled trial