The surgery for dental implants in atrophic sites is a constant challenge. The sinus lift has some recognized techniques; however, the use of low morbidity and low-cost techniques is a trend in surgery. This study aims to identify implant stability observed in dental implants installed in an atrophic maxillary sinus using the lateral window technique without bone graft or biological barrier. A clinical series included 20 patients with 25 conical design dental implants installed, with 1 year of follow-up performed. Bone height was analyzed in the preoperative stage and at 1 year of follow-up using panoramic radiography. All the implants were installed using a lateral window sinus lift, respecting a minimum insertion torque of 35N. Four months later, the second surgery installed the healing abutment and then the prosthetic abutment; the fixed prosthesis on the implant was performed conventionally. After 1 year of follow-up, only one implant was lost at the healing abutment installation stage, the remaining 24 implants were rehabilitated conventionally with no issues. All the implants were stable 1 year after surgery; an average bone gain of 4.9 mm was observed between the preoperative stage and the 1-year follow-up, a statistically significant increase (P > 0.05). The immediate implant with primary stability in maxillary sinus lift using the lateral window approach, without bone grafts or biological barriers, has a high survival rate and facilitates new bone formation around the implant.