We search for \gamma -ray and optical periodic modulations in a distant flat spectrum radio quasar ( FSRQ ) PKS 0426-380 ( the redshift z = 1.1 ) .
Using two techniques ( i.e. , the maximum likelihood optimization and the exposure-weighted aperture photometry ) , we obtain \gamma -ray light curves from Fermi -LAT Pass 8 data covering from 2008 August to 2016 December .
We then analyze the light curves with the Lomb-Scargle Periodogram ( LSP ) and the Weighted Wavelet Z-transform ( WWZ ) .
A \gamma -ray quasi-periodicity with a period of 3.35 \pm 0.68 years is found at the significance-level of \simeq 3.6 \sigma .
The optical-UV flux covering from 2005 August to 2013 April provided by ASI SCIENCE DATA CENTER is also analyzed , but no significant quasi-periodicity is found .
It should be pointed out that the result of the optical-UV data could be tentative because of the incomplete of the data .
Further long-term multiwavelength monitoring of this FSRQ is needed to confirm its quasi-periodicity .