Phytohormone auxin plays an important role in fruit development and is perceived by the TIR1/AFB family of F-box proteins as auxin receptors involved in auxin signal pathway. Cucumber (Cucumis sativus L.) fruit development is either parthenocarpic or non-parthenocarpic. However, little is known on TIR1 and AFB participation in the early stage of cucumber fruit development. In present study, TIR1 and AFB2 were isolated from cucumber. CsTIR1 and CsAFB2 were highly expressed in leaves and ovaries. Their transcript levels decreased in parthenocarpic and pollinated fruits, but continuously up-regulated in aborted fruits, indicating that down-regulation of CsTIR1 and CsAFB2 may be in favor of cucumber fruit set and development. The transcript levels of CsTIR1 and CsAFB2 were significantly induced in leaves by NAA, 6-BA, GA₃, ABA, and ethephon. The expression levels were up-regulated by ABA and ethephon treatments. This expression patterns was accordant with the aborted fruits. Thus, CsTIR1 and CsAFB2 may be important regulators during cucumber fruit development.