The economics of a catalytic process using a fluidized conversion zone and a relatively expensive catalyst for converting an oxygenate to light olefins are substantially improved by recovering and recycling effluent contaminating catalyst particles from the product effluent stream withdrawn from the conversion zone which are present despite the use of one or more vapor-solid cyclone separating means to clean up this effluent stream. The contaminating catalyst particles are separated from this product effluent stream using a wet scrubbing zone and an optional dewatering zone to recover a slurry containing the contaminated particles which, quite surprisingly, can be successfully directly recycled to the oxygenate conversion zone or to the associated catalyst regeneration zone without loss of any substantial amount of catalytic activity thereby decreasing the amount of fresh catalyst addition required to make up for this source of catalyst loss.