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We present time series analyses of three-decade long radio observations ofthe BL Lacertae object AO 0235+164 made at the University of Michigan RadioAstronomical Observatory operating at three central frequencies of 4.8 GHz, 8.0GHz and 14.5 GHz. We detected a quasi-periodic oscillation of $\sim$965 days inall three frequency bands in the light curve of the effectively simultaneousobservations, along with strong signals at $\sim$1950 d, $\sim$1350 d, and$\sim$660 d. The periodicity is analyzed with three methods: Data CompensatedDiscrete Fourier Transform, Generalized Lomb-Scargle Periodogram and WeightedWavelet Z-transform. These methods are chosen as they have different analysisapproaches toward robust measurement of claimed periodicities. The QPO at$965\pm 50$ days is found to be significant (at least $3.5\sigma$) and ispersistent throughout the observation for all three radio frequencies, and theothers, which may be harmonics, are comparably significant in at least the 8.0GHz and 14.5 GHz bands. We briefly discuss plausible explanations for theorigin of such long and persistent periodicity.

Quasi-Periodic Oscillations in the long term radio light curves of the blazar AO 0235+164