The relationship of suture bite size, suture diameter, and fascial thickness to strength of wound closure was studied in cadaveric linea alba. All soft tissue was removed from the fascia of 12 abdominal walls that were cut into 346 test sections. A single suture loop was placed in each section, simulating laparotomy closure with interrupted technique. Suture bite size (0.3, 0.6, 0.9, 1.2, 1.5, and 1.8 cm) and gauge (00, 0, 1, and 2) were randomly assigned. The force and energy required to pull out suture loops were measured. Mean linea alba thickness was greater above the linea semicircularis than below (1.19 vs 0.77 mm; p less than 0.001). Similarly, mean pullout force was greater above the linea semicircularis (58.2 vs 31.6 N; p less than 0.001). Regression analysis found that fascial thickness and bite size accounted for 68% of observed variability in pullout force. Suture diameter was unrelated to pullout force. Optimum security was obtained with bites of at least 1.2 to 1.5 cm.