[carbonyl-(11)C]WAY-100635 ¿[(11)C]N-(2-(4-(2-methoxyphenyl)-1-piperazin-1-yl)ethyl)-N-(2- pyridy l)cyclohexanecarboxamide¿ is a positron-emission tomography (PET) radioligand for in vivo imaging of the 5-hydroxytryptamine(1A) (5-HT(1A)) receptor. This paper assesses and summarises various different modeling strategies for the quantitative analysis of the radioligand. The models considered are based on a compartmental description of the ligands behaviour and include both plasma input analyses, requiring the additional monitoring of blood activity, and a reference tissue approach, which relies solely on the tomographic tissue data. Parameter estimates of specific binding are presented for a set of test-retest data, obtained from six normal volunteers who were scanned on two separate occasions, allowing for an assessment of normal binding values and their reproducibility.