A study of plasma thiamin pyrophosphate (TPP), erythrocyte transketolase activity (TK), TK affinity for coenzyme (Km TPP), as well as whole blood pyruvate (Pyr) and pyruvate/lactate (Pyr/Lac) has been performed in 14 men and 22 women healthy control (20-25 years old), 4 men and 49 women, age matched fibromyalgia (FM) (ACR criteria) 5 men and 6 women with chronic alcoholism and 3 men and 5 women with myofascial pain syndrome (MPS). Pyr was significantly increased in alcoholics and FM ; Pyr/Lac was significantly increased in FM only. TK was decreased in alcoholics. Km was significantly increased in FM. TPP was significantly decreased in alcoholics and markedly increased in MPS. Nutritional thiamin abnormalities, observed in alcoholics and functional thiamin abnormalities observed in FM, are not demonstrated in MPS, in spite of a trend for increased pyr and pyr/lac.