The effect of four plant growth regulators (PGRs) on crop performance, fruiting pattern, yield and fiber quality in cotton (Gossypium hirsutum L.) was evaluated in field experiments for two years in Greece. All four PGRs (Cytokin, Cytoplex, PHCA and Atonic) increased seedcotton yield and differences were related to effects on plant growth and development. Number of sympodia with 2 bolls and total boll number increased significantly in the Cytokin and Cytoplex treated plants, while Atonic and PHCA had a lesser effect. All PGRs increased boll retention, either at first or at second position. Lint quality was not affected by PGRs, although in some experiments positive effects were found in fiber maturity and strength. It is concluded that the four PGRs have the potential to control plant growth and enhance yield.