The carnitine content of the culture media for normal and pathological human muscles, including a case of systemic carnitine deficiency (SCD) was measured and the carnitine concentration was the same in all normal and pathological muscle culture media. Carnitine was never detected in growth medium. Some fibroblasts and myoblasts were filled with neutral lipids in SCD. 14C-palmitate added to the medium was incorporated by SCD fibroblasts or myoblasts to the same concentration as in normal or pathological cells. Factors other than carnitine seem to account for the lipid accumulation of SCD in cell culture.