Serial serum creatine phosphokinase (CPK) levels were determined in a series of 50 patients following cessation of a heavy drinking spree. Despite the fact that only six patients had overt clinical evidence of an acute myopathy, CPK levels were elevated in 21 of 24 patients with delirium tremens (DTs) and in 15 of 20 patients with acute alcoholism without myopathy or DTs. The CPK level was normal in 11 chronic alcoholics with no history of recent drinking. A typical pattern of CPK elevations was noted. Following a lag of 24 to 48 hours during which CPK levels were normal, levels rose rapidly reaching a peak in four to five days and then fell to normal. Spinal fluid levels of CPK were zero even in the presence of marked elevations in serum CPK.