Clinical examination following an exercise test that elicits the symptoms of lower leg pain is most helpful in diagnosing the causes. Location of swelling, pain, impaired muscle function and impaired nerve function should all be analysed. History and clinical signs alone are insufficient to establish the diagnosis of chronic anterior compartment syndrome, and for this reason intramuscular pressure recordings have an important role in diagnosis. Different techniques for pressure recording and different pressure parameters are reviewed. Muscle relaxation pressure during exercise and intramuscular pressure at rest after exercise are the best parameters to study. Fasciotomy relieves pain in between 60% and 100% of patients. Closure of a fascial defect is never indicated, because it decreases the compartment size and may precipitate an acute compartment syndrome. Recording of nerve conduction velocity is a helpful complement in the diagnosis and evaluation of superficial peroneal nerve compression. Decompression by local fasciectomy and fasciotomy of the lateral compartment gives good results in more than 50% of patients. The value of periostitis as a clinical sign and the possibility of chronic pain following eccentric exercise are discussed.