Mangrove plant group distribution was stuclied along the Chiapas Coast by means of 177, 10 m x 10 m quadrats taken in 16 sites in the four most important lagoon systems. To classify the quadrats by importance values permited us to distinguish eight mangrove groups. Around 73% of the total variance of the quantitative data was accounted by the first two principal axes in the ordination of quadrats. The first axis was significantly associated to the field salinity (r=-0.76, g. l.=15, p<0.001), which decreases from NW to SE as a consequence of the amount of water continental runoff. Finally, it was found that the height of Laguncularia racemosa (r=0.56, g. l. =60, p=0.0001) and Rhizophora mangle (r=0.59 , g. l. =124, p=0.0001) , but Avicennia germinans (r=0.24, g. l.=47, p=0.09), were inversely related with salinity concentration and with the contribution of freshwater from the drainage systems corresponding to each coastal lagoon system.