<i>Background:</i> The positron emission tomography (PET) radiotracer Pittsburgh Compound-B (PIB) is an in vivo ligand for measuring β-amyloid (Aβ) load. Associations between PET PIB and cerebrospinal fluid (CSF) Aβ1–42 and apolipoprotein E Ε4 (<i>APOE </i>Ε4) have been observed in several studies, but the relations between PIB uptake and other biomarkers of Alzheimer’s disease (AD) are less investigated. <i>Method:</i> PET PIB, PET 18Fluoro-2-deoxy-<i>D</i>-glucose and different AD biomarkers were measured twice in CSF, plasma and urine 12 months apart in 10 patients with a clinical diagnosis of mild to moderate AD. <i>Results:</i> PIB retention was constant over 1 year, inversely related to low CSF Aβ1–42 (p = 0.01) and correlated positively to the numbers of the <i>APOE</i> Ε4 allele (0, 1 or 2) (p = 0.02). There was a relation between mean PIB retention and CSF ApoE protein (r = –0.59, p = 0.07), and plasma cystatin C (r = –0.56, p = 0.09). <i>Conclusion:</i> PIB retention is strongly related to CSF Aβ1–42, and to the numbers of the <i>APOE</i> Ε4 allele.