Background: During management of Achilles tendon rupture, determination of tendon-end approximation, either clinically or by ultrasound is difficult, following brace application of during loading. The Radiographic Achilles Tendon Loading Angle (RadATLA) is proposed as a method of measuring ankle position whilst loading in a brace during the management of Achilles tendon rupture. This study aims to determine the reliability and reproducibility of the RadATLA. Methods: A loaded true lateral ankle radiograph including the fifth metatarsal head was taken when wearing a brace at the 6-week time point in 18 patients (19 ankles). following Achilles tendon repair or reconstruction. The RadATLA was compared with the Tibio-talar angle, other radiographic and clinical measures used to quantify foot and ankle position during the first 6 weeks of early rehabilitation in a resting position and during loading. Results: The intra-rater reliability of both angles was found to be good (>0.8). The RadATLA was found to have an excellent intra-rater reliability with Intra-class correlation of (ICC) 0.992−0.996 (95%CI 0.889−0.999), standard error of the measurement (SEM) 1.03–3.65 and Minimal Detectable Change (MDC) 2.86−10.12. The inter-rater reliability was good with ICC of 0.798−0.969 (95%CI−0.03 to 0.964), SEM 2.9–7.6, and MDC 8.1–20.9. The RadATLA loaded at 6 weeks in all patients was at mean (SD) (range) 41.9˚ (16.5), (18.5−75.9). There was a significant difference between the patients in the Repair group compared with patients in the Reconstruction group both in RadATLA loaded at 6 weeks: 35.6˚ (11.2), (18.5−56.5) versus 55.5˚ (19), (20−75.9), (p = 0.01). The amount loaded in all patients was at mean (SD) (range) 29.2Kg (17.7), (2−56) and the percentage Body Weight was 30.7% (19), (2.1−63.2). There were no differences between the groups neither in amount loaded nor in percentage Body weight (p = 0.614−0.651). Conclusions: The RadATLA is a reliable and reproducible angle and can be used to determine the position of the ankle, when loaded in a brace during rehabilitation following Achilles tendon rupture.