Sinus membrane thickening is a common maxillary sinus disease. However, a consensus has not been reached on the effect of sinus membrane thickness on the transcrestal sinus floor elevation. This retrospective study evaluated the perforation and bone formation at transcrestal sinus floor elevation sites with different sinus membrane thicknesses. A total of 117 sites in 87 patients treated with transcrestal sinus floor elevation were included in this study. The surgical sites were divided into four groups according to the baseline sinus membrane thickness: Group A (0 to 1 mm), Group B (1 to 2 mm), Group C (2 to 4 mm), and Group D (> 4 mm). CBCT scans were taken before surgery, immediately after surgery, and 6 months after surgery. The mean baseline sinus membrane thickness was 2.16 ± 2.54 mm, and the mean residual alveolar bone height was 6.58 ± 1.85 mm. The mean endosinus new bone height was 3.76 ± 1.95 mm. The perforation rate and endosinus new bone height showed no significant difference among the groups (P > .05). The incidence rates of membrane thickening and perforation were significantly higher in smoking patients (P < .05). Membrane thickening without ostium obstruction may have little impact on transcrestal sinus floor elevation surgery in regards to perforation rate and bone formation. In addition, smoking may be a risk factor for membrane thickening, and the sinus membrane is more likely to perforate during transcrestal surgery when the patient has a history of smoking.