Tetrahydroxy bile acids (THBAs) are hydrophilic and are present at minimal or undetectable levels in healthy human adults, but are present at high levels in bile salt export pump (abcb11)-knockout mice. The roles of THBAs in human cholestatic diseases are unclear. We aimed to investigate the presence of THBAs in patients with infantile intrahepatic cholestasis and its correlation with outcome. Urinary bile acids (BAs) were analyzed by GC-MS. Data were compared between good (n = 21) (disease-free before 1 year old) and poor prognosis groups (n = 19). Good prognosis patients had a higher urinary THBA proportion than poor prognosis patients 25.89% (3.45–76.73%) vs. 1.93% (0.05–48.90%). A urinary THBA proportion >7.23% predicted good prognosis with high sensitivity (95.24%), specificity (84.21%), and area under the curve (0.91) (P < 0.0001). A THBA proportion ≤7.23% was an independent factor for decreased transplant-free survival (hazard ratio = 7.16, confidence interval: 1.24–41.31, P = 0.028). Patients with a confirmed ABCB11 or tight junction protein 2 gene mutation (n = 7) had a minimally detectable THBA proportion (0.23–2.99% of total BAs). Three patients with an ATP8B1 mutation had an elevated THBA proportion (7.51–37.26%). In conclusion, in addition to disease entity as a major determinant of outcome, a high THBA level was associated with good outcome in the infantile intrahepatic cholestasis patients.