We investigate variability of optical and near-infrared light curves of the X-ray binary GX 339 - 4 on a timescale of days . We use the data in four filters from six intervals corresponding to the soft state and from four intervals corresponding to the quiescent state . In the soft state , we find prominent oscillations with an average period P = 1.772 \pm 0.003 d , which is offset from the measured orbital period of the system by 0.7 per cent . We suggest that the measured periodicity originates from the superhumps . In line with this interpretation we find no periodicity in the quiescent state . The obtained period excess \epsilon is below typical values found for cataclysmic variables for the same mass ratio of the binary . We discuss the implications of this finding in the context of the superhump theory .