Post-infectious fatigue or post-infectious neuromyasthenia (PIN) is an illness characterized by persisting fatigue and disability after apparent acute infections. In most cases the illness is attributed to a chronic Epstein-Barr virus infection. Symptoms include weakness and fatigue in the absence of physical findings or significant laboratory abnormalities. These patients are frequently depressed and have considerable disability resulting in prolonged loss of time from work. The illness may be persistent or can be relapsing, but often lingers for two years or more. There is no effective therapy. Pin is probably caused by an acute infection occurring in patients who are psychologically susceptible. They require emotional support, reassurance and explanation.