To the Editor: In the recent letter from Larkins and Molesworth1 various statements are made on which I would like to comment.

From time to time everyone becomes physically or mentally exhausted, whether or not it is related to activity.

For some people this exhaustion becomes disabling. They deserve understanding and sympathy. We must do everything we possibly can to assist them to recover and to try to find possible causes.

Larkins and Molesworth acknowledge that chronic fatigue syndrome is a serious, disabling illness. When does ordinary exhaustion become disabling?

I would agree that at this stage there is no clinical evidence that the condition is primarily psychological. Nor is there evidence that it is primarily physical. There may be a mixture.

What is the "significant evidence" of a range of biological abnormalities occurring in people with CFS? What are these biological abnormalities and what physiological evidence is there for each one of these abnormalities to produce fatigue?

Larkins and Molesworth state that treatment plans should be "within the capabilities of the patient": is there evidence to indicate that stimulating each patient to do just that little more each day will do harm?

It was stated that scientific evidence of the aetiology, pathology and treatment is grossly deficient. It is in fact absent. There is no evidence at all. Research is certainly required.

One of the problems is that, as soon as a medical advisor informs a patient that investigations have shown no serious abnormality, the patient often goes away and says to himself or herself or family that the "doctor said there is nothing the matter with me and that it is all in my head". Nothing could be further from the truth. Something is the matter and it is up to us to find it out.