Twenty two Army patients with synthetic (Gore-tex) anterior cruciate ligament (ACL) reconstructions were reviewed (mean follow up 18 months). Reconstruction appeared to abolish the pivot shift sign in all cases, but some subjective instability persisted in all but 6 patients. Outcome was also assessed by medical (PULHHEEMS) grading: 6 patients were fully fit (graded L2), 7 returned to moderate activity but not full fitness (L3), and 9 remained severely incapacitated (L7 or L8) with 4 of this group being medically discharged. Specific operative complications included: prosthesis breakage (3 partial, 1 complete), infected prosthesis(1), and problems with the tibial screw(3). The range and frequency of complications was similar in other series. Physical fitness is an integral part of a soldier's job, placing particular demands on the knee and on surgical repair of knee injuries. Reports on the Gore-tex ACL prosthesis in other groups have been more encouraging, but there are difficulties in comparing this study with others. ACL insufficiency remains a serious problem, with implications for a soldier's fitness and career. The Gore-tex prosthesis improves stability but does not always allow a soldier to return to full fitness.